The front needs to come off. 1 screw behind the soap drawer , 1 holding the bottom panel on and the either 2 or 4 on the bottom corners. You will also need to release the front retaining ring for the door seal.
Once the panels off , all will be revealed. The heater has a pressure seal so the best way to get it out is to disconnect all connections , undo the middle nut until its almost on the end of the threaded shaft then give it a gentle tap to push the thread in….this should take a lot of the pressure off the seal and then its a case of wiggling it out.
POWER OFF IF ATTEMPTING REPAIR