1. From the Home screen, go to Settings.
2. Select General.
3. Scroll down to Reset and press it.
4. Choose to Erase all files and settings from the drop-down menu. This will completely erase everything from your phone system, allowing it to start up as if it were brand new.
5. To continue, enter your device passcode if requested.
6. Finally, select the option to confirm the system reset.
When the reset is complete, your iPhone will immediately reboot and load with factory default settings. This necessitates your personalization.