Welcome to the Forums
this is on a chev?
I have a 2006 lexor, yours is likely similar
You'll need a 10mm wrench to remove 4 bolts holding the seat to the swivel mount, 1 each corner
I have a billion 10mm wrenches- to make this easy I bought a stubby 10mm with a ratcheting end on amazon
It tight under there.
the seat is not too heavy, lift it up to the rear, and out the side door.
the swivel mechanism can then be removed, this may be greasy. not sure of wrench size needed.
I only took the top plate off of mine to clean and lube the bearings
on mine there is a "box" which holds all my manuals and stuff under the swivel, I never looked to take this out.
I use my swivelled pass seat all the time as we leave the bed made up.
as you know the floor between the seats gets hot and that is where I pile my reflectix window covers, with dog bed on top. it works well
cheers, Mike