A factory reset will erase all data from your device and is irreversible. This is good to do if you are going to trade in or sell your device. It will wipe all of your personal information from the device.
From the Home screen, drag down the Notification panel.
Drag down the Quick settings panel.
Tap the Settings icon.
Scroll to Backup & reset.
Tap Backup & reset. Before proceeding, make sure to back up all data, pictures and video you want to keep. Resetting the phone deletes all files on the device.