OMG that is freaking hilarious. I got some of that stuff all over my hands once, it is near impossible to take off! They're going to have to shave her head clean and just wait till the skin cells on her scalp die out to get rid of the rest. I had a can in a closet that I had used for a single quick spray, you're not actually suppose to keep them after you use them once but I really did not want to waste a full can. So I go to open the top off, but the valve inside had not sealed right so the contents was under pressure inside the cap, but the cap was solid enough so it does not pop. When I opened it, it was equivalent to dumping half the can directly into my hands, and in a panic mode not wanting any on my floor I captured the rest (now spraying non stop) with my cupped hands so I can run to the garbage with it.
After managing to get the worse of it off I was left with flakes of the stuff all over my hands, it looked like I got severely burned, and took a good week or so for it to clear up. I could pick at it every now and then and some would flake, but pretty much just had to rely on the skin cells falling off over time with the foam on it.
But putting that stuff in your hair.... LOL. Ya, that's going to be a fun time.