1. At First Turn Off your Call Phone press power key.
2. After turn off your device Press And Hold Volume Up + Volume Down + Power Key To turn on your device until Show logo On Screen.
3. Now You Can See Android recovery menu Use Volume Down Key To Scroll And Select This Option "wipe data / factory reset" Press Power Key Confirm.
4.After That Scroll and Select "Yes -- delete all user data" Than again Press power key. wait few second.
5. after finish hard reset process Now Select "reboot system now" Press Power Key To confirm.
Done