Simple, leave it where it is. Cut the wire if you wish. I've used transducers mounted on the inside of the hull (solid not cored) by epoxing it in place. Just check that it can couple through the hull, easy method is as posted below, in a ziploc bag with water to couple to the inside of the hull.
Next time you haul, remove the old if you are still inclined.
Cal 9.2 #19 SilverSwan