It looks as though it could be snipped off with nail clippers. Be careful not to get the tongue when doing it, though. Probably taking the tortoise to a vet would be the safest option.
A big update!!
In a shop in Romagna..the place where i take the tort 6 years ago..i think they have an online shop..minizoo rinaldiWow! What a change! I'm happy to know that he is "usual self" now. You've been doing great with caring for him and courageous to clip the "tooth"!
He drinks a lot because he eats a lot and water is supporting digestion.
I think if you don't see any bleeding and rot - you may stop betadine (it slows down wounds regeneration).
By the way, where have you got Mazuri in EU? (I'm hesitating to order from US because of the price )