You can either restore the iPad through iTunes, or you can got to Settings > General > Reset, and Erase all Content and Settings.
Either will place you back into the out of the box state. When you activate the iPad it will walk you though the setup, including creating a new Apple ID if needed.
If the iPad is iOS 5 or later all you need it is an available wi-fi connection. If it is iOS 4 or earlier you will need a computer running the most recent version of iTunes.