Thanks for asking cause I was out there getting ready for a Kayaking trip and got curious, and removed one of mine. I decided to check and see if they were working and what do you know one of mine is shot.
I don't know what the manual says (I'm too lazy to look) but it was easy enough. Push the lens to one side according to the arrow (both of mine are pushed toward the passenger side) and it pops out, then take a small screwdriver and prize the little tabs that are on the insert out of the holes in the lens cover. Then the wire un-clips from the back. I assume that whole unit you have left is then replaced, I'm about to find out cause I need one. :doh: