Thank-you, Shrew! This forum has provided a lot of good advice over the years!
Here is a photo...not our boat but the interior is the same. The part of the settee we want to remove is under the big window and wraps around under the starboard small window. The seat cushions come off. There is a piece of electronic equipment that is connected to the surround sound system that has to be fixed (we think lightning fried the power supply), and it's located behind the back on the curve between the two windows. It's almost as if it was installed before the settee was installed. We can't find any screws anywhere where it might be attached.