Back up your data if possible
Open Settings
Tap System
Tap Reset options
Tap Erase all data factory reset
Tap Reset phone
Enter your PIN, pattern, or password if prompted
Tap Erase everything
Wait for the phone to restart and complete the reset
If the phone will not open Settings, power it off
Press and hold the Power and Volume Down buttons until the boot menu appears
Use the volume buttons to select Recovery mode
Press the Power button to confirm
When the Android robot appears, press and hold Power, then tap Volume Up once
Select Wipe data/factory reset
Confirm the reset
Select Reboot system now