You can fold the seat bottom up, and remove the plastic organizer tray from underneath. Then you will have the carpeted floor with only a small hump in the middle.
The seat will still fold down and be useable. The organizer does not support the seat bottom.
If you want to remove the seat completely, remove the 4 bolts holding the bottom brackets, and lift the entire seat assy up. The seat back has U hooks that slide down into loop brackets to hold it in place.