How do I remove bottom section of back seat in.

Ususlly seat cushions are either clipped or bolted on at fron below the cushio. For bolts you can easilty see the mounting point. If it is clipped on, you would need to lift the front portion (at about 1/4 way of length of cushion) of cushion as high as possible and push your hands under the seat to push/pull at the locking tab.
If the above are not found whereby you have only two prongs plugged into the floor panel, you would need to push you hands between the seat and cushion to look for a bolt holding the cushion. Pull cushion out from rear and tilt it up to release the front plugged in points.

For foldable seats/cushions, you would need to flip the seat down and peell carpet off to locate holding bolts.