Since there is no precise information about this issue, I recommend using the classical way of factory resetting a phone. To do this, charge the phone to 50% or more, then turn if off and press the following key combination: Power + Volume Up or Power + Volume Down until you see the Android logo. That means you are on the right track to access the Recovery Mode. While you are in the recovery mode, select Wipe data/Factory Reset and confirm the operation with the Power button. Reset the phone and that's it.