I want to say you have to remove the liner along the wall on the tail end of the trunk, but I'm not totally sure what you're asking here.
To remove it, simply pull the push-tabs out. I think there is four or so of them, two on each side of the liner. Careful not to tweak them too hard or they'll break. They're pretty cheap to replace, but if you're like me and hate having anything not in its place, then you'd do best to do it with care. I use my hands, but I know theres a few tools that would certainly work better.
This should allow you access to the back, and presumably, (I stress presumably, I haven't messed with the taillights enough to know) the entire assembly of both the right and left tail lights. In some model years, this is also where your PATS unit is, so if you ever need to disable your alarm entirely (generally not advised, unless your car is a repo like mine and the alarm likes to go off at random) you can do it here.
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