At first switch off the cell phone.
Then hold and press the Volume Up + Power button until you see Android logo on your screen.
Afterwards select using the Volume buttons option "wipe data/factory reset", and confirm that with Power button.
Choose "yes" from the menu, and accept it with Power button.
Now accept option "reboot system now" using Power button.
Success! The factory reset is done.
Then hold and press the Volume Up + Power button until you see Android logo on your screen.
Afterwards select using the Volume buttons option "wipe data/factory reset", and confirm that with Power button.
Choose "yes" from the menu, and accept it with Power button.
Now accept option "reboot system now" using Power button.
Success! The factory reset is done.