Before you start performing a factory reset you need to know that all your application that was installed on your device will be removed. With that being said, shutdown the your device, and with the help of a paper clip, press the small button which is positioned right next to the USB port. Simultaneously press the Power button and keep them pressed until the Android logo appears. After that do the same steps again until a menu appears. Using the same paper clip to select Wipe data/ factory reset option and hit OK by using the Power button. Wait a few moments and reboot your phone.