You found your old phone in a drawer, it has been sitting there for a year, collecting dust.
You decide to sell it, get a few pounds, clear some clutter.

But before you list it online, you need to do something critical, you need to wipe it clean.

Not just delete a few photos, not just log out of apps, but completely remove every trace of your personal information so the next person cannot find it.
Here is exactly how to do that, step by step, for phones and computers.

Why Deleting Is Not Enough

Here is something most people do not know, when you delete a file on your phone or computer, it is not actually gone.
The device marks that space as available for new data, but the old data stays there until something overwrites it.

Anyone with basic recovery software can undelete your photos, your messages, your browsing history, even your passwords.

One study found that 67% of used hard drives sold on eBay still contained recoverable personal data including tax returns, medical records, and family photos.
Do not be that person.

A proper wipe does not just delete, it overwrites every bit of data with random information so nothing can be recovered.

What You Need Before You Start

Gather these things before you begin:
1. Your device charger, the wipe process can take time and you do not want the battery to die
2. Your passwords, you will need to log out of accounts like iCloud, Google, and Find My Device
3. A computer if you are wiping a hard drive using special software
4. A few hours of patience, some wipes take minutes, some take hours

How to Wipe an iPhone

Apple makes this relatively straightforward, but you must do the steps in the right order
Step 1: Back Up Anything You Want to Keep
If you are moving to a new phone, back up your old one first

With iCloud:

Go to Settings, tap your name, tap iCloud, tap iCloud Backup, tap Back Up Now

With a computer: 

Connect your iPhone to your computer, open Finder (on Mac) or iTunes (on Windows), select your device, click Back Up

Step 2: Sign Out of iCloud and Find My iPhone
This is the step people forget, and it causes problems
If you do not sign out, the next owner will be locked out and you will still be connected to the device

How to do it:
Go to Settings, tap your name, scroll down and tap Sign Out, enter your Apple ID password, tap Turn Off
This removes your iCloud account and disables Find My iPhone

Step 3: Sign Out of Other Accounts
Go to Settings, tap Passwords & Accounts, tap each account (Google, Facebook, etc.) and remove them
This is not strictly necessary if you factory reset, but it is good hygiene

Step 4: Erase All Content and Settings
Go to Settings, tap General, tap Transfer or Reset iPhone, tap Erase All Content and Settings
You will be asked to confirm, enter your passcode, and the phone will begin erasing
The process takes 5-15 minutes depending on how much data you had

Step 5: Watch for the Hello Screen
When the wipe is complete, the phone will restart and show a "Hello" screen in multiple languages
This is how you know the wipe was successful, the phone is now as clean as the day you bought it

How to Wipe an Android Phone

Android phones vary by manufacturer, but the general process is the same
Step 1: Back Up Your Data
Go to Settings, tap Google, tap Backup, make sure Backup is turned on, tap Back Up Now

Step 2: Remove Your Google Account
Go to Settings, tap Accounts (or Passwords & Accounts), tap Google, tap your account, tap Remove Account
You will be asked to confirm

Step 3: Remove Your Screen Lock
Go to Settings, tap Security, tap Screen Lock, choose None (or Swipe)
This prevents the next owner from being locked out by your old pattern

Step 4: Factory Reset
The location varies by phone brand
On Google Pixel: Settings > System > Reset Options > Erase All Data (Factory Reset)
On Samsung: Settings > General Management > Reset > Factory Data Reset
On OnePlus: Settings > System > Reset Options > Erase All Data
On most other Android phones: Settings > System > Reset Options > Factory Data Reset
You will be asked to confirm, the phone will restart and begin erasing

Step 5: Watch for the Setup Screen
When the wipe is complete, the phone will show a setup wizard asking you to choose a language and connect to Wi-Fi
This means the wipe worked

A Warning About Android Factory Resets

Here is something most articles do not tell you.
On some Android phones, especially older ones, a factory reset does not completely overwrite all data.

The reset marks the data as deleted, but recovery software can still find it.
If you are selling an Android phone and are truly concerned about your data, take these extra steps.

Enable encryption before resetting:
Go to Settings > Security > Encrypt Phone (or Encrypt Tablet).
This may take an hour, but it ensures that even if data remains, it cannot be read without the encryption key.
Then perform the factory reset.

For maximum security (older phones only):
Fill the phone with nonsense data before resetting.
Download a large video file and copy it to the phone repeatedly until the storage is full, then delete it, then fill it again.
This overwrites your old data with new data, then the factory reset wipes everything.

How to Wipe a Windows Computer

Windows computer is well known for its high-quality tools to do the job.
Step 1: Back everything up
Use an external HDD or cloud-based service to copy all files you wish to retain (photos, documents, ect.). Verify that your backup is complete before moving forward.

Step 2: Sign out
1. Remove your Microsoft account by going to Settings > Accounts > Your Info. 
2. Unlink all web browsers (i.e., Chrome, Firefox, Edge) so that the saved passwords stored in these browsers are no longer stored or synced back to your newly formed desktop image.
3. Deauthorize iTunes or other software that has device limits

Step 3: Use Reset This PC
Windows 10 and 11 have a built-in reset feature

How to find it:
Click Start, type "Reset this PC", select the option
Or go to Settings > Update & Security > Recovery
Click Get Started under "Reset this PC"

Step 4: Choose the Right Options
You will see two options:
1. Keep my files (do not choose this, it leaves your personal data)
2. Remove everything (choose this)

Then choose:
Local reinstall (faster) or Cloud download (more thorough but requires internet)
Then click Change Settings

Step 5: Enable Data Erasure
This is the most important setting, toggle the switch to "ON" for "Clean drives"
This tells Windows to overwrite your data instead of just marking it as deleted
Without this setting, someone could potentially recover your files

Step 6: Start the Reset
Click Confirm, then Next, then Reset
The process takes 1-4 hours depending on your drive size and speed
When it finishes, the computer will restart and show the Windows setup screen, ready for the new owner

How to Wipe a Mac

Mac computers have excellent built-in wipe tools
Step 1: Back Up with Time Machine
If you are moving to a new Mac, back up your old one using Time Machine
Connect an external drive, go to System Settings > Time Machine, click Back Up Automatically

Step 2: Sign Out of Everything
1. Sign out of iCloud: Apple Menu > System Settings > Apple ID > Overview > Sign Out
2. Sign out of iMessage: Messages > Preferences > iMessage > Sign Out
3. Sign out of FaceTime: FaceTime > Preferences > Sign Out
4. Deauthorize iTunes: Account > Authorizations > Deauthorize This Computer

Step 3: Erase the Drive
Restart your Mac and immediately hold down Command + R until you see the Apple logo
This boots into Recovery Mode.
When the Utilities window appears, select Disk Utility, click Continue.
In Disk Utility, select your main drive (usually called Macintosh HD), click Erase.
Name it "Macintosh HD", choose APFS or Mac OS Extended (Journaled), click Erase.

Step 4: Reinstall macOS
After the drive is erased, close Disk Utility
From the Utilities window, select Reinstall macOS, click Continue.
Follow the prompts to install a clean copy of the operating system.
When the installation finishes, the Mac will restart and show the setup wizard.
You can now shut it down by holding the power button, the new owner will complete the setup.

How to Wipe a Hard Drive or SSD (For Computers You Are Not Keeping)

If you are selling a computer but keeping the hard drive, or selling the hard drive separately, you need a different approach

For Traditional Hard Drives (HDD)

Traditional hard drives are easy to wipe completely
Use DBAN (Darik's Boot and Nuke):
Download DBAN from its website, write it to a USB drive, boot your computer from that USB drive, follow the prompts to wipe the drive.
DBAN overwrites every sector multiple times, making data recovery impossible.
A full wipe can take 6-24 hours depending on the drive size.

For Solid State Drives (SSD)

SSDs are different, they have wear-leveling and overprovisioning that can hide data from overwriting tools

For SSDs, the best method is to use the drive manufacturer's secure erase tool:
1. Samsung: Samsung Magician
2. Crucial: Crucial Storage Executive
3. Western Digital: WD Dashboard
4. Kingston: Kingston SSD Manager

These tools send a special command to the drive that instantly resets all memory cells, the process takes seconds
Do not use DBAN on an SSD, it will not work properly and will shorten the drive's life

What About Phones That Do Not Turn On

If your phone is broken and will not power on, you have fewer options
If the screen is broken but the phone turns on:
Connect it to a computer and attempt the factory reset through recovery mode

For iPhone: Connect to computer, put in recovery mode (specific button combinations vary by model), use Finder or iTunes to restore

For Android: Connect to computer, use ADB commands or manufacturer recovery tools

If the phone is completely dead:

Your only option is physical destruction.
Drill through the memory chip, smash it with a hammer, or take it to an electronics recycling center that offers data destruction services.
Do not sell a dead phone without destroying the storage, someone could repair the phone and access your data.

What About SD Cards and SIM Cards

Your phone may have an SD card or SIM card that contains personal data

SD Cards

Remove the SD card before selling the phone
If you are keeping the card, simply remove it
If you are selling it with the phone, wipe it using your computer:
1. Insert the card into a card reader
2. Open File Explorer (Windows) or Finder (Mac)
3. Right-click the drive and select Format
4. To avoid losing your data, be sure to uncheck “Quick Format” when formatting your hard drive.

SIM Cards

SIM cards have all your contact numbers and messages on them.
Make sure to remove your SIM card before you sell your phone.
If you're keeping the same phone number, just transfer your SIM card from your old phone to your new phone.
If you're getting a new phone number, destroy the old SIM card by cutting the card so that it completely cuts through the small metal chip in the SIM card.

Common Mistakes to Avoid

Mistake 1: Only doing a factory reset without signing out
If you factory reset without signing out of iCloud or Google, the next owner will be locked out and you will still have the device attached to your account
This is called Activation Lock on iPhones and Factory Reset Protection on Android

Mistake 2: Choosing "Keep My Files" on Windows
This does not remove your personal data, it only removes apps

Mistake 3: Forgetting to remove the SIM and SD card
These cards contain personal data, remove them

Mistake 4: Assuming a quick format is enough
Quick format only marks the space as available, it does not erase the data
Always choose full format or use drive cleaning software

Mistake 5: Selling a device without wiping because it is "old and nothing is on it"
There is always something on it, browsing history, saved Wi-Fi passwords, cached emails
Wipe it anyway

A Quick Checklist Before You Sell

Go through this checklist before handing over your device

For any phone:

1. I back up all items I wish to keep.
2. I signed out of Cloud/iCloud for Android or Google for Apple phones. 
3. I turned  off Find My Phone etc.
4. I have removed the SIM card from the phone and SD card etc. 
5. I've preformed a Factory Reset (which means all my data is gone).
6. The phone is now showing my newly set up phone instead of the old phone screen

For any computer:

1. I have backed up everything I want to keep
2. I have signed out of all accounts
3. I have deauthorized iTunes or other software
4. I have used Reset This PC with "Clean drives" enabled (Windows)
5. I have wiped the drive and reinstalled the OS (Mac)
6. The computer now shows the setup wizard

The Bottom Line

Selling your old phone or computer is a great way to get some money back and keep electronics out of landfills. But your personal data is worth more than the sale price
Take the extra hour to wipe your device properly. Sign out of accounts, encrypt if possible, overwrite the data, and verify that the device boots to a setup screen

The next person who buys your device should get a clean device, not your photos, your messages, or your passwords.
Do it right.

FAQ Section

Is a factory reset enough to wipe my phone completely?

For iPhones made in the last few years, yes, Apple uses strong encryption that makes data unrecoverable after a factory reset, for Android phones, it depends, older Androids may leave recoverable data, enable encryption before resetting for maximum safety

Can someone recover data after I reset my Windows PC?

If you used Reset This PC with the "Clean drives" option enabled, your data is overwritten and cannot be recovered, if you did not enable clean drives, someone with recovery software could potentially undelete your files

How long does a secure wipe take?

iPhone and Android factory resets take 5-15 minutes, Windows Reset with clean drives takes 1-4 hours, Mac drive wipe and reinstall takes 1-2 hours, DBAN on a large hard drive can take 6-24 hours

What should I do with a broken phone I cannot wipe?

Physically destroy the memory chip, drill through the phone's motherboard where the storage chip is located, smash it with a hammer, or take it to a professional electronics recycler that offers certified data destruction

Do I need to wipe my SD card separately?

Yes, factory reset does not wipe SD cards, remove the card and either keep it or wipe it using your computer with a full format (not quick format)