How do I remove the plastic thing behind the seats?
 

there is a plastic thing covering the trunk, thast behind the back seats, any pointers on how to remove this piece im thinking of using this pieve to host some speakers but i need to build some custom haousing for the speakers

If you're talking about the top rack on the hatchback 3, it slides right off. Slide the cover towards you until the two sides click out then lift. Then you unhook the cords from the hatch.

nop, its the sedan one, the one with a trunk