HTC Gratia hard reset

A factory reset is a drastic measure. It permanently erases all your personal data and customized settings, and also removes any programs you have installed

HTC Gratia hard reset Factory Resetting

Performing a factory reset via settings
The most convenient way to do a factory reset is via the phone settings.
From the Home screen, press MENU and then tap Settings.
Scroll down the screen, and then tap SD & phone storage > Factory data reset.
On the Factory data reset screen, tap Reset phone, and then tap Erase everything.

Performing a HTC Gratia factory reset using phone buttons

If you cannot turn on your phone or access the phone settings, you can still perform a factory reset by using the buttons on the phone.
With the phone turned off, press and hold the VOLUME DOWN button, and then briefly press the POWER button.
Press VOLUME DOWN to select CLEAR STORAGE, and then press POWER to reset the device.