- Power off your phone.
- Hold and press together Volume Up + Power button, until you see Recovery Mode.
- Next from the menu choose option "wipe data/factory reset" using Volume buttons to scroll options, and Power button to confirm operation.
- Then you will see next menu, and from this menu select option "Yes -- delete all user data".
- After this process, accept option "reboot system now".
Hard Reset will erase all of your data
All described operations you are doing at your own risk.