^^^ This.
And once you get most of it off, don't worry if there is some left that stays put. It shouldn't bother him. Once he starts getting rehydrated and eating more regularly, he'll probably shed a few times for you more frequently. I would keep his enclosure humid for a few weeks to help with the shed and his next shed (like around 70% humidity).
At his size, feed one appropriate sized prey every 7-10 days - no more. And the prey should be no bigger around than the snake. Boas are not ball pythons and do better on slightly smaller and less frequent meals, relatively speaking.
Do get a couple pics of his eye and we'll go from there.![]()