There should be a centre expansion plug in each of those. The cover you want to remove is the rad cover.
Pry out the centre of one, then pry out the main part.
I used a pair of offset needle nose pliers to flex the tabs on my grill and it worked great.
also, with those kind of plugs don't put any downward pressure when you are unscrewing them.
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2004 40th Anniversary V6.
Cold Air Intake, OR Xpipe with dual flowmasters, SCT Xcal3, Mach 1 Grill Delete, Terminator Side Scoops, Limo Tint, Shorty Antenna, Custom Audio... more to come...
The best way to get those plastic screws out is to get a flat tip screw driver, pry gently on the plastic round insert, then unscrew the screw with your other hand. And don't push down on the screw driver with pressure, lightly turn the screw, it will come out, the license plate bulb covers are the same way. GL