These two hacks will completely disable the good and evil witch skin tone overlays, so the look just like normal sims. The sim's original skin tone will show as if the were a neutral witch, and they will keep their sparkles if they are evil/good enough. There are two files, one for good witches and one for bad witches, so you can decide if you want to change both of them or not. I used a different technique from HystericalParoxysm, mine are slightly smaller.
Please note that this may not take effect immediately on loading the lot, if you Sim still has the overlay on their face, take them to a mirror. Apply some face paint, then remove it. Save. Their face should be normal then.