Yah, those things are really tough to get off, once they are on. I am working on the exact same grill and had to do that two days ago. In my case, the bottom pan was toast, so I just manhandled it off.
Honestly, I tilted it up to one side, stuck a screwdriver into the tab, pried it inwards, and kicked it. One side popped up so I went to the other side and repeated the process. Looked ridiculous, but it worked.