1. Press and hold the Power button to turn off the phone.
2. Press the Volume Up & Power buttons simultanously. Release it when the Android logo pops up.
3. Now enter Recovery Mode by press-holding Power.
4. Select the wipe data/factory reset option. Navigate to it with Volume and select with Power button.
5. Press Power to confirm by selecting Yes.
6. Lastly, select reboot system now. Done.