I used a piece of plastic (like a flat blade screwdriver) to lift it up, and just pulled it off. It helps to start at the clip above the one that connects to the lower piece, and work down.

I did have a hard time getting the bottom clips out, but I was able to pull it up enough to get a pair of needlenose pliers to help pull out the clip. It may help to push up on the lower panel (e.g. towards the spoiler) while pulling out the tab. Actually, I think it is a little easier to remove the screws and pull the lower panel off first.

When I did it, the metal clip came out with the tab on the side piece.

Hope this helps...