Its great that you’re asking questions and getting some opinions. It’s also great he has time outside his hutch, but that reinforces the dislike of being in it. It could be synonymous with cage bar biting. Potentially get an xpen to surround the hutch, so it can be open, making it seem less like he’s being kept from a large part of his territory? Right now, the hutch is something barring him from going around if he wanted to.
It will be difficult to curb this behavior, so I suggest making it difficult to do, rather than trying to get your rabbit to learn not to do it. Can you get cardboard pieces and layer and cover up the walls? Or maybe line them with fleece if he doesn’t like chewing on it?
Do not trim your rabbit’s teeth. Have a vet do it. Doing it without proper tools and experience can cause fractures in the teeth that go down to the gum, exposing the gum to air and bacteria, becoming a breeding ground for infections. A vet will make the decision if your rabbit’s teeth, front and/or back, are at a point where your rabbit needs them trimmed so he can eat and not be in discomfort.
How is his eating and how are his poops?
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.