Sorry, I'm not describing this very well. Let me try again.
I am trying to remove the chrome piece with the turn signal. That's what I mean by "gill." When I tried to remove that, both it and the surrounding black honeycomb "grill" came out together (both halves of still together). Once I had it out there was just a big hole in the fender. I unplugged the turn signal and taped off the wire so it wouldn't fall in.
Next I tried to squeeze the tabs of the chrome gill to extract it from the black grill but I couldn't get it all the way out. I was able to separate it at the back (the end closest to the door when installed) but when I got to the tabs at the deepest part (behind the ///M3 badge) they would not budge. I could have broken them off but didn't want to do that. I'd rather keep the stock parts.