If you’re selling or giving away your old Android smartphone or tablet, you can use a factory reset to get rid of all your data and applications on the device.
You can also use a factory reset if you want to completely wipe your phone and start fresh. To perform a factory reset, go to your settings. The option is under your System tab. Select Reset and confirm that you would like to remove all apps, accounts, and data from the device and return it to its factory presets. Your device will then erase the data and reboot, ready for a new start.