If you can carefully & manually pick it off, that's what I'd do.Many snakes get creeped out by baths, but a lot of that has to do with their loss of traction & the sudden weird feel of water all over their body, which by the way, is why you MUST be sure it's not too hot. Remember we're 98.6* so the water will feel cool to us when it's right for the snake at about 85*. Then if you add traction (maybe an underwater hand-towel) it should help. Keep the water shallow, about half of the snake's height, & keep moving the water over them by hand...they should not have to swim to stay above water. (they can swim but get tired & you never leave them alone) But to make this work, mites must be eliminated not only from the snake but from any place in the cage they can hide or leave their eggs, because they're real into big extended families. Mites are so very icky, & can carry diseases to your snake.