you can factory reset from recovery mode by following these steps.

Using the volume buttons to navigate and the power button to select:

Power off then hold Power + Volume DOWN simultaneously until the bootloader screen appears,
Use the volume DOWN button to navigate to Recovery Mode and use Power to select,
You should then see an Android lying down with chest opened,
Press Power + tap volume UP just once and immediately release both,
Use the volume DOWN button to navigate to Wipe Data/Factory Reset,
Press Power to select,
Press volume DOWN and use Power to select 'Yes',
Wait for the process to complete and then reboot the phone.