Yeah for me personally its just easier to stick in the xdk recovery disk and wipe everything. then i know EVERYTHING is gone.
If your running a 5xxx xdk launcher though you can press x to open up the tools / settings menu and there is wipe and factory reset in there
Also curiosity killed the cat. Why do you need to wipe it before selling? If its your code then sure but if its other peoples code then you should back it up.