If possible can you get a picture of it, try putting a damp
slightly warm towel and put it on the toe and rub it, and try and
get some circulation running, I wouldnt cut it off right now, is your
chicks skin pink or does it have black skin or speckled? because it
could be there skin coloring.
I wouldn't cut it off just yet. How long was it on his toe? May it has just discolored his toe. I can't really tell from the pic. I would let it go a couple of days to see if it wears off or spreads. This way you will know for sure.
It looks pretty dead to me there. Just keep it clean and keep an eye on it... hopefully it does not spread as that would be a sign of gangrene. I had a chick cut it's tip of its toe and eventually the tip fell off and he grew into a handsome 8 lb RIR rooster, minus half the tip of his toe.
I know this isn't a chicken, but my middle son's hamster got bedding wrapped around her foot and hung by it for (hours?) while we slept. Her entire foot looked that bad for quite awhile. I massaged it and made sure it felt warm (so I knew it wasn't dead). Now the foot is just as perfect as the others.