Make sure you’re not also gifting your personal data to the receiver of your smartphone. For Android smartphone, Google says would-be sellers should "enable encryption on your device and apply a factory reset beforehand”. Simply performing a factory reset on its own won’t prevent your data from being recovered.
Android Smartphone Data Wipe
- Backup all your data, because once it's gone, it's gone.
- Next, plug the charger into the device so it's getting power for the deletion process. This is important because the process can take hours.
- Go to Settings > Security > Encrypt phone (or Encrypt tablet) to begin the process on Android 4.4 or lower, or go Settings > Security > Screen lock to begin the process on Android 5.0 and higher.
- You will be guided through the process. Set a strong password. Don't bother encrypting the SD card because you can pop this out rather than wiping it. This process can take over an hour, so be patient and make sure you have the time.
- Go to Settings > Backup & reset > Factory data reset and then tap Reset phone.
Once this process is complete your data is gone. Technically, it's still written there on the flash memory in what is now reported as free space, and will eventually be overwritten. Because it's encrypted recovering it would be difficult.
iOS smartphones Data Wipe:
- If you paired an Apple Watch with your iPhone, unpair your Apple watch (For more information see https://support.apple.com/en-us/HT204568
- Backup your iOS Device-(for more information see https://support.apple.com/en-us/HT203977)
- Tap Settings > iCloud. Scroll down and tap Sign Out. In iOS 7 or earlier, tap Delete Account.
- Tap Sign Out again, then tap Delete from My iPhone and enter your password.
- Go back to Settings and tap General > Reset > Erase All Content and Settings. If you turned on Find My iPhone, you might need to enter your Apple ID and password.
- If asked for your device passcode or Restrictions passcode, enter it. Then tap Erase iPhone.
- Contact your carrier for help transferring service to a new owner.
That's it! Your data is now gone, and you're safe to pass the smartphone on.
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