How to Hard Reset Sony Xperia Z Ultra C6802 device
STEP ① - Tap on "Apps" icon of your mobile device.
STEP ② - Launch the Settings app on your Sony Xperia device.
STEP:③ - Scroll down to reach “Backup and Reset” option.
STEP:④ - Tap on “Factory data reset” option.
STEP:⑥ - And finally "Erase everything" from your device.
STEP:⑥ - Restarting your device. Your device is ready to use now.