Have you checked the lower front of the seat bottom cushion for bolts or clip areas? Maybe try carefully running your fingers in the area between the carpet and the cushion to see if there are areas where things feel different. If you don't find any bolts in those areas, try pushing back on the cushion there and lifting.
Once you get the lower cushion out you'll probably find a couple of bolts holding a couple of tabs in for the rear seat back. Once you unbolt those you may just need to lift the seat back up and unhook it from the upper edge, or there could be a couple of bolts in the trunk.
-Rod