
Do you want to give or resell your smartphone? Here is how to proceed to be sure that it will no longer contain any of your personal data.
The decision is made, you want to change your smartphone. But before giving away or reselling your current device, you must make sure that it no longer contains any of your data. We show you the procedure for the operating systems of Google and Apple.
For Android devices
1 – Preliminary steps
If you want to back up your data, you can connect your smartphone to a computer with the supplied cable and perform a transfer. Another solution is to insert a microSD card and save your data there with the file manager of the smartphone (or download a file manager from the Play Store). Important folders are DCIM (photos), Download (downloads), Movies (movies), Music (audio files), and Pictures (other images).

You can also back up some data to your online Google account, in order to restore it to another Android device. This is for example practical to automatically find the parameters of your applications or system data (passwords, etc.). To do this, go to Android settings (gear-shaped icon accessible from the top of the screen) and type backup in the search area (this area is present at the top of the screen in Android 7 and 8). You can also go to the section Backup and reset, then Back up my data in Android 6/7. For Android 8, you have to go to System, then Backup & restore and Backing up my data.

Then turn on the save switch. If you are only interested in backing up your photos and videos online, we recommend that you use Google Photos and enable the setting there. Save and synchronize. For music, there is no equivalent but you can optionally store your files on Google Drive.
2 – Disable the screen lock
In the Android settings search box, type screen unlock Where screen lock (the exact mention depends on the version of Android and the manufacturer’s overlay). For Android 6/7, this option is located in the section Security, then Screen lock. For Android 8, go to Security & confidentiality, then Lock Screen and Screen unlock mode. Select No in the choice of locking / unlocking.

3 – Delete the Google account
In the Android settings search box, type accounts. In the section Accounts (Android 6/7) or Accounts & users (Android 8), select Google. Tap on the three small vertical dots icon and choose Delete account. On some smartphones, tap the trash can icon at the bottom of the screen to delete the account (click on the image below for a larger view).

If you have other accounts, such as a Samsung account, delete them as well.
4 – Optionally encrypt the data
When resetting the smartphone, the data is no longer accessible but remains present in the flash memory and could be recovered with specialized software. If you want an extra level of security, you can encrypt the data on your smartphone (it may already be). To do this, go to the section Security settings for Android 6/7 or Security & Lock Screen for Android 8. Then check if the encryption option (Encrypt phone) is present (it is not available on all models).

If it is already enabled, you don’t need to do anything. Otherwise, activate the function by tapping Encrypt phone. You will then need to enter a PIN code or password to start encryption, if it is not already active. Connect the smartphone to the mains for this operation.
5 – Reset the smartphone
In the settings search box, type reset. For Android 6/7, you can also go to Backup and reset (or Backup and reset). For Android 8, go to System then Reset. Depending on the device, then tap Restore factory settings Where Restore factory values. Then tap on the button Reset (or Restore) at the bottom of the screen to start the procedure.

Once the operation is complete, turn off the smartphone by keeping the on / off button pressed.
For iOS devices
1 – Preliminary steps
If you have an Apple Watch, you must remove the link between the watch and the iPhone using the Apple Watch app (tab My watch and function Unpair Apple Watch).
To back up your data to your iCloud account, go to iPhone settings (gear icon on the home screen). Tap on the name of your Apple ID (first entry in Settings), then tap iCloud. Scroll down and select ICloud backup. Turn on the save switch and tap Save now (Click on the image below for a larger view).
Be careful, however, for the backup to be initiated, you will need to ensure that the iPhone is plugged into the mains and connected to an operational Wi-Fi network.

The other method is to plug the iPhone into your computer. You can then transfer your photos, of course, but you will need to use iTunes to make the full backup of your data.
If your information is valuable and you share the computer you are backing up on with someone else, we recommend that you request that it be encrypted. Just avoid forgetting the password that will allow you to open this protected archive.

2 – Disable iMessage
It is no longer necessary to turn off iPhone location before you can reset it. The reset procedure takes care of this. That’s always that less to do. Nevertheless, remains an essential step, especially if you plan to leave the iOS world for a while. You need to unlink your phone number from the iMessage feature.
In iPhone settings, tap Messages. Then turn off the switch iMessage.

3 – Disconnect iCloud and other services
As in step 1, tap on your Apple ID name in settings and scroll down. Tap on Logout.

Enter your Apple ID password and tap Deactivate. The device will be disconnected from iCloud, iTunes, as well as the App Store.
4 – Erase all your data
To reset the device, select General in the settings and scroll down. Tap on Reset.

Finally select on Clear content and settings to complete the operation. You will then have to validate your choice several times. Because once the operation, no salvation, no turning back.