Yup. Just dealt with those little $&@#ers a couple weekends ago. They're NOT screws. If you look at the side, you'll notice that it's actually three pieces: the rubber on top, the plastic that it's locked into and a plastic base piece. Wedge a small flat-head screwdriver between the two plastic pieces (ignore the "notch" on the side where the rubber piece goes down more and the top plastic piece gets thin) and gently twist to lift the top plastic and rubber assembly out of the base. Then remove the base.
Then (if you haven't already found them) you'll need to lean over the middle of the bumper to see where the two hook-like tabs on the bumper latch into the two squarish holes in the metal reinforcement beam, about 3 in. closer toward the center than the rubber-topped fasteners were, under that black plastic piece. There's just enough space to fit a finger in each. Push the bumper in toward the rear slightly and lift the tabs and it'll come right off. Have a friend help or put a towel/blanket down under it so it doesn't get scratched up (any more than it is).
But before you do any of that, make sure you've removed the screws holding the trailing corner of the bumper in front of the wheel to the fender. To get at them, peel the piece with the two missing screws toward the tire. In the pic you posted, notice the spot toward the top where the part that faces the tire curves in about 3 in. from the corner? The screw is roughly straight up under that, maybe back a bit. It's exactly the same as the 11 screws that were holding the splash guard to the rear lip of the bumper. It's also the hardest screw to remove without dropping so I highly recommend using a magnetic screw driver or magnetic box-end socket driver. It comes out straight down. If you haven't removed them yet and you release the bumper, then the bumper may bend and ripple the paint on the corner near this screw. (Didn't happen to me when I was working on mine, just have seen what auto paint does when the plastic it's painted onto bends.)