Using the settings reset to factory settings

Slide open the Notifications panel, tap Key.
Touch Backup and reset.
Tap Reset phone.
If you want to delete media on HTC Desire 500 and other data, select Erase all data.
OK Tap.

reset to factory settings using the hardware buttons

If you do not have access to HTC Desire 500 can not open the device or phone settings, you can reset your phone to factory settings using the hardware buttons on HTC Desire 500.

Remove the battery, replace the battery, wait a few seconds.
Press and hold the button REDUCE THE SOUND LEVEL, press and hold the POWER button.
Wait for the screen with the three Android images to appear and release the button REDUCE POWER AND SOUND LEVEL.
FACTORY SETTINGS VOLUME DOWN button to select RESET, then press the POWER button.