To remove the bottom seat, you need to remove the heel panels first, then undo the two bolts. It should slide straight out, but if you have heated rear seats watch out for the wiring.
Now you should be able to see all of the screws underneath the seat back. Undo these, and the seat belt bolts. Before you try to lift the seat up, carefully remove the plastic clips from the top of the seat, where the seatbelt goes through. These break VERY easily. Once these are off, you should be able to lift the seat back up, feed the seatbelts through, then remove the seat.