1. Find "Reset"
2. Restore settings only
If you select Reset All Settings, all phone settings are restored but contacts, audio files, video clips and appointments aren't affected.
Press Reset All Settings.
Press Reset All Settings to confirm.
3. Restore settings and data
If you select Erase All Content and Settings, settings, contacts, audio files, video clips and appointments are deleted.
Press Erase Now.
Press Erase iPhone to confirm.