The only way to unlock your phone is to perform a factory reset. This means that all you have installed on your device will be gone after this process is done. Therefore, to perform a factory reset you will need to pass a few steps. First of all shutdown your device. After that, open the phone in the Fastboot Mode (keep pressed the Volume Up key and the Power key until it opens). Next, choose from the menu the factory reset and press OK using your power button. Wait until the process is ready, reboot your phone and that is all.