You can perform a factory reset by using the volume and power keys. First power off the phone then follow the steps:

Press Volume Up + Volume Down + Power Buttons -This gives you two options select Volume Up (Recovery Mode) -Scroll Down with Volume Down to "Wide Date/ Factory Reset" -Select with Menu button on buttom left of screen -Once reset is done select first option "Reboot System Now" to Reboot.

Now you have done a factory reset on the phone.