Well, they all start with effects programmed don't they, so you have to find a patch you want to edit, then turn the rotary knob to go through each "module" (i.e mod, amp, fx, eq etc) and turn them off using whatever it says in the manual. Then, to save the patch, press save (I think, it explains this too). Then you have a new patch!
There's no function to "clear" a patch, so that you can just add in what you want, although that would be useful!