Removing the back seat is not needed but as austin said there are four nuts in side where the arm rest folds into. All you need to do is remove the rear deck cover. To do so the rear pillar plastics must be unclipped by pulling on them inward careful it is plastic once loose if you look at the edge of the rear deck where it it meets the seat back you will see some metal tabs fold these up. Depending on how yiur speakers are mounted you may have to remove those as well. You will see the cover should now be loose granting you better access to the nut at the top of the strut.
