While the phone is off.
1. Press and hold volume down plus the power key.
2. Release the power button when ag logo is shown.
3. Release the the volume down button when you are in factory mode.
5. Use the volume down to scroll and the volume up to select.
6. Scroll down to "wipe data factory reset"
7. Scroll down to "yes delete all user data".
8. Scroll to "Reboot".
CommeComment below if further assistance.