drill em out.
that's the only way i've successfully removed those bad boys
Regarding the 2 lame plastic rivets in the fender, I actually used a screw driver and stuck my hands in there and popped them out from the bottom up. It was a lot of work, and I did get some scuffs on my arm. Nonetheless, they came out. I reused them again and they hold my fender firm as it did originally. But yeah if I did those again I would definitely just cut and replace