The HTC Touch HD uses the Windows Mobile operating system, which is a very straightforward OS found on a wide variety of smartphones and tablets alike. Formatting the internal memory on a HTC Touch HD will remove all the data you have stored on internal memory, but it won’t delete any aspects of the Android operating system. For example, all your apps, music, photos, videos, numbers (stored on phone), messages (stored on phone), and downloaded wallpapers will be deleted, but stock software, such as default wallpapers, will stay on the phone.
Touch the Start button and press “Settings.” Press “More…” and then touch the “Master Clear” option. Text your password into the box that appears. If you haven’t set the password, the default password will be “0000.”
Touch the device that you want format in the next screen and it will be immediately formatted. If you have an external SD card connected to the phone, it will appear in this section as well. If you want to format the internal memory (not a removable SD card), press the first option, which is the internal memory.