how to factory reset xperia z3
1 Turn your phone on and unlock the screen. 2  Go into your Settings app. 3  Scroll down to âBackup and restoreâ and select that option. 4  Pick the âFactory data resetâ option. 5  Select âErase Phoneâ. 6  Select âErase everythingâ. 7  Agree to a warning that will pop up. 8  You are set, the phone will do its thing and restart itself. Go into your Settings app. 2  Scroll down to âBackup and restoreâ and select that option. 3  Pick the âFactory data resetâ option. 4  Select âErase Phoneâ. 5  Select âErase everythingâ. 6  Agree to a warning that will pop up. 7  You are set, the phone will do its thing and restart itself.