Once you get under there, you'll know what to do. I cant exactly recall what to do, but I think its 2 plastic screws (fog light equipped one) and unhooking the clips.
When I painted and glassed mine, it took 2 minutes to take the bottom grill out and 2 minutes to put it back in.
When I painted and glassed mine, it took 2 minutes to take the bottom grill out and 2 minutes to put it back in.