How to wipe your phone or tablet before you sell it

Here is how to wipe your personal data from a mobile device the right way before trading up to a new model.

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Lexy Savvides/CNET

Trading in or selling your old mobile device? Wipe it the right way to reduce the risk of personal data falling into the wrong hands.

Remember that no method apart from physically destroying the device and its storage is 100 percent foolproof -- data may still be recoverable with the right tools.

These tips are for the three main mobile operating systems, but if you have an older phone or an alternate OS, check the manual for full details on how to wipe your device.

Before you start:

  • Back up all your data, including contacts.
  • Remember to remove the SIM card and any external storage such as a microSD card.
  • Log out of services like email and social media, then clear the data from these apps if you can.
  • Perform a separate encryption and wipe of data on the microSD card as well if you don't plan to use the card in a new device.
  • Keep the serial number of the phone or tablet on file for your records.

Android

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Lexy Savvides/CNET

The simplest way to wipe your Android device is to perform a factory reset. However, this often only clears data at the application level, and other information such as SMS and chat messages can be restored with some standard data recovery tools.

Instead, CNET's Dan Graziano has a full rundown on how to effectively wipe data on your Android phone or tablet, which begins with encrypting your device first through the Settings menu.

You won't need any special tools, just a bit more patience than it takes to simply press the restore option within the settings.

Once the wipe is complete, remember to also revoke access to the phone from services such as Facebook and Google. To remove devices from your Google account, head to myaccount.google.com, click on "Sign-in & security," then under "Device activity & notifications," find the model you have wiped. Press Remove next to the Account access option.

iOS

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Lexy Savvides/CNET

Apple devices that support iOS 5 or later include hardware encryption when you set a passcode. If you perform a wipe using the method below, the encryption key is also overwritten, which makes it very difficult for anyone who wants to recover the data.

Step 1: Before starting the reset process, make sure to turn off all services, starting with Find My iPhone. Do this by heading to Settings > iCloud > Find My iPhone. Enter your Apple ID password when prompted.

Step 2: Sign out of iCloud completely. Head to Settings > iCloud and find Sign Out at the bottom of the page. For iOS 7 devices, choose Delete Account.

If you delete all your data manually without signing out of iCloud, it will also delete the content from iCloud as well -- which is something you definitely don't want.

Step 3: Turn off and sign out of other services including iMessage and Apple ID.

For iMessage, go to Settings > Messages > toggle the iMessage option. For your Apple ID, go to Settings > iTunes & App Store > tap your Apple ID email address and then Sign Out.

For added peace of mind you may also want to sign out individually from any other linked services and apps, such as Facebook or Twitter.

Step 4: Start the wipe process. Go to Settings > General > Reset > Erase All Content and Settings. Confirm the selection.

Step 5: If you have registered your device with Apple by its serial number, remove it from your support profile by logging in with your Apple ID at supportprofile.apple.com

Windows Phone

Josh Miller/CNET

Windows Phone only offers encryption for business customers. The easiest way to wipe a Windows Phone 7, 8 or 8.1 device is to perform a factory reset and then load dummy data to overwrite traces of the original data.

Step 1: Open up Settings from the main apps list. Find About and then tap Reset Your Phone.

Step 2: Confirm the action and then wait for the phone to wipe.

Step 3: Connect the phone to a PC and open My Computer. If you are connecting via Mac, download the Windows Phone app. Find the phone, which should show up as a removable device, and open it.

Step 4: Load dummy data onto the phone by dragging and dropping from another folder. Don't use your personal photos or documents here; instead choose files that contain no identifiable metadata that could be traced back to you, such as video or music files. Try and fill the phone with as much dummy data as possible.

Step 5: Reset the phone again using the same method as in step 1. Repeat the dummy data load a few more times to ensure all your original data is overwritten.

Step 6: Perform a final reset.

Log in to your Microsoft account at account.microsoft.com and under Devices, click the phone you just wiped. Then, remove the device from your account.

Update, December 26, 2015:Revised Android and Windows Phone device removal information.

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