We have two qualified veterinarians on this forum who own chameleons and one is also a breeder. Hopefully, they will see this thread and respond for you. Me personally, I would be taking him to see a vet and not attempt something like that myself.
No, I would let a professional handle it. It may dry up and fall off on its own. I can't tell much from the photo on my phone, but the risk here is infection, so if it's starting to look moist, raw, etc., you're in better hands with a vet.
I had something similar happen with a male of mine. At first it was just a tail kink but then it became necrotic and very quickly ran up his tail. A good portion had to be amputated, and he's ok. But always better to have a vet involved.
If that is tail rot which it definitely looks like it is. It will need to be amputated before the infected tissue to stop the progression. It is best to take your animal to a vet to do this kind of thing. Left untreated it will consume more of the tail.
Don't cut it. I had the same thing happen to one of mine, only much further up the tail than that. I thought hers would need to be amputated, but it has been a year and she is fine and her tail is intact. It is severely crooked and ugly, but she's fine. Keep an eye on it and let a vet cut it if it comes to that.
Ok....I posted at the same time as Ferrit..... go with what she says, she's a vet!