there are just 2 little die cast dowels on the back that snap into tang'd holes in the fender. You simply just pull. Obviously you don't want to drive a screwdriver behind it, but you just have to pry on it. I popped mine off with a screwdriver using a wooden paint stick underneath as a lever fulcrum so as not to touch the paint.
If you break off the dowels, don't worry. I used 3M tape to stick mine back on after repainting. they aint going anywhere.