Before you try the factory reset or hard reset on your device, make sure that you have backup your important files. Restoring the default settings or factory reset your device will delete all your existing files and will go back to its initial state.
>>> Turn off your phone.
>>> Press and hold together Volume Down + Power button for 20-30 seconds.
>>> Release the buttons when you see an Android icon.
>>> Press the Home to see Recovery Menu.
>>> Select "wipe data/factory reset" by using Volume buttons, and Power button to confirm.
>>> Then choose "Yes -- delete all user data".
>>> Confirm operation "reboot system now".
The instruction provided is the general steps on how to Hard Reset and Factory Reset.If the instruction will not work, please make a comment and we will immediately find the correct procedure. Thanks.