In order to hard reset a HTC Radar, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
HTC Radar device will be brought back to the default configuration of a brand new device.
1. Turn off the phone by holding down the Power button.
2. Now press and hold Power & Volume Down buttons.
3. Commence the Factory reset with a press of Volume down button.
4. Your phone will reset and restart - this can take up to five minutes.