First thing to check is whether there is a furnace or duct work under or behind the sofa. Either of those could play havoc with your plans.
As far as actually removing it, typically there are 4-6 bolts or lag screws holding it to the floor. Sometimes a bit awkward to get at them, but not a big deal. Getting the sofa out of the RV, on the other hand, can be a challenge unless the sofa can be further disassembled. On our last coach, there were only 4 floor screws and the ends of the sofa came off. We could move it around inside the coach well enough, but not sure if we could get it out through the big lounge window of not. The entry door would have been impossible.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC