Hi,
How long is it since he ate?
I would let him have at least 48 hours from when he ate to digest his meal then let him soak in 86f water half way up his sides for about 15-30 minutes then let him slither through a washcloth to try and get that off.
The only time you really should keep trying to remove stuck shed is when it completely encircles the snakes body like it normally does with the tip of the tail. :)
dr del