The one that if you were sitting in the back seat would be at your shoulders? Take the whole armrest panel off. Easier access if you remove the back seats. The speaker cover doesn't come off from the outside.
when i did mine i didnt take the whole thing off. i just cracked it and was able to get to em. but good luck its not that bad. just do the top panel not the rest cause i thought all this crap had to come off but just mess with the top