always a good idea to check under your back seat for corrosion and pocket change
to answer the original question (from memory so please jump in to correct/clarify if needed):
the frontside of the back seat lower is held in place by passing under 2 clips/hooks in the sheetmetal of the floorpan, one on each side, about 4-6" in from the door
the backside of the back seat lower frame has 2 large gauge ~1/4" "wires" sticking out about 4" further with a 1" loop on its end, one on each side about 6" from the wheelwells. these are fastened down by a Large bolt threading into a special reinforced Nut-sert on the floorpan.
(are they the same bolts holding the seatbelt ends ? I forget)
once those 2 bolts are removed you can lift up the back of the seat and thus unhook the front of the seat
if you dont need to remove the seat, rather just need to lift the front of the seat up to get carpet in/out or perhaps retrieve something which may be under the back seat:
depending on your strength, dexterity, and the integrity of the back seat, you can sometimes, on each side, push the front of the back seat in, then up, to release the front edge from the clips w/o undoing the Large bolts ; getting the clips back in can be challenging too

but its possible if U got the right moves