I planned on washing her today, and found out that when she is dry she has what seems to be dried, dead, turtle shell. is this normal? I also washed her shelll with pure white vinegar and it still didn't come off.
Was the dried shell in sections in the shape of her scutes? That's definitley shedding and SHOULD NOT BE AIDED. Helping the scutes come off can cause a lot of damage if they're not ready to come off. Shedding is a long process and is best left alone.
Cleaning the shell doesn't need to be done very often, but it should be done with a super soft brush or q-tip. Vinegar isn't necessary unless they have algae or something on his shell.