They're typically just bolted in. How to access those bolts.. well, you didn't say which model of excavator you had in mind. On some, you might be able to access the bolts without removing seat cushions.. on others, not so much.
The seat is not upgradable easily. If you are interest in reupholstering, you could upgrade the seat that way.
Yes, you can replace it yourself or get a seat cover to go over the seat. You can learn about reupholstering your seats by visiting http://monkeyfighter.com/upholstery.html.
If you have a knack for do-it-yourself projects, then reupholstering a chair is doable. Be sure to practice on smaller furniture to ensure you get the hang of things before reupholstering a sofa. It depends on the design of the chair. To remove and recover the seat portion only is fairly easy; a number of website detail the procedure. If the chair is upholstered, like a Parsons design, it is easier to make slip covers.
An affordable company to reupholstering restaurant chairs is called IMad. It is located in Wisconsin but I dunno where you live.
there are two bolts in the back of the seat. remove them and then slide the seat back about an inch and remove
To remove the back seat of a 1998 Toyota Corolla, you will need to remove the carpet to expose the bolts for the seat. Then, loosen the bolts by removing the nuts. You can then remove the seat.
On newer models, you have to move the seat all the way forward, remove side trim cover, remove seat belt anchor bolt, remove seat rails retaining bolts, tilt seat upward, disconnect wires, remove seat...
you must remove the bolt behind the rear seat and remove the rear seat then you will see 2 small Allen head bolts remove them and the seat will come right off.
The bolts are visible at the base of the seat. Remove them and lift out the seat.
Move seat fully forward, remove side trim, remove seat belt retaining bolt, remove seat tracks rear bolts, flip seat upwards, disconnect wiring, remove seat.....
The rear seat is not designed to be removed. You can remove the center seat and slide the rear seat forward.
how to remove 2004 scion back seat