I am attempting to remove cracked glass/plastic cover on tail light assembly. I am not tring to replace the bulbs

That is not a cover, the taillight is an assembly, sold as one piece. you can order it on line or through any of the parts stores. lift your hatch. look on both sides and you will see large plastic nuts that you turn by hand. remove those nuts, remove the panel and you will see I think 3 more nuts, remove those and they will release the whole taillight to the outside, unplug all 3 wiring harnesses, (use a small flathead screwdriver to release the plugs) plug into the new taillight assembly.

Thanks, now it makes sense.