Cut the skin off and a clean suture line and Bob's your uncle, f'n witch doctors. DO NOT LISTEN TO THEMIn the early stages, a blend of strong dish soap (I like Ultra Dawn) emulsified with some paint thinner/kerosene will help much. The toxin molecule is greasy, too greasy to partition well into alcohol. Once the rash has set in, the problem is an in-skin reservoir of unmetabolized toxin, and at that point a strong oxidizing agent (bleach) is the best recourse to kill the reservoir of the bad stuff.
"Oxi Clean" type percarbonate products are less effective ime.