There's another thread on this, its a real pain in the @ss. You have to remove one of the rivets in order to get them to come out. From another thread:
Remove the bulb/ wire plug first, there is a plastic rivet that holds the inner and outer fender together at the leading edge, just below the marker light... you need to pop out the center of the rivet with a small probe/nail/allen wrench or the like (you REALLY have to push on it to get it out) hang on to that little ribbed plastic rivet center, you'll need it to put the rivet back in place, then remove the rivet body. after that the inner part can be flexed in and down to pop the tab that holds it to the outer portion loose. after that i think there was two tabs that held the light lens in place i think you had to squeeze those & then finaggle it out.
I did this when i put on the RR little useless guards. It sounds complicated, but it took about 5 minutes to do per side, hardest part was getting that damn rivet to pop out.