In order to hard reset a HTC HD7S, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
HTC HD7S device will be brought back to the default configuration of a brand new device.
1. Press Power button to turn the phone on.
2. Hold down both Volume buttons and, while you hold them, press Power button for two seconds.
3. Instructions will appear on screen, please follow them.
4. Your phone will reset & restart. Done.