you don't wetsand a frame, unless of course you have tons of spare time and gobs of unused elbow grease.
you got to your local auto parts store and get the paint stripper in the red can with the pic of an airplane on it, (i forget the exact name)
use a small 2" wide paint brush to apply it, wait about a 1/2 hour and pressure wash all the paint off, repeat on places you missed, the frame should be degreased befrorehand so the stripper can do it's job on the paint
easiest, quickest way to clean your frame !!!!!