I guess the process is the same as it is for an iPod Touch.
I gave mine away recently and 'cleared' it via iTunes. I started by Restoring the original settings [there is a button for that on the first window you see when the iPad/touch is highlighted/lit] - then when asked if I wished to instal my old content from the backup [I forget the exact phrase they use] I said no. At some point I had the opportunity to change its name which I did.
When I tested all had been cleared.