Not sure if I had the same type set up as you but I recently removed all the seatbelt bars from my motorhome to do a remodel. The large bracket under the dinette bench seat was bolted to the floor w/ 8 bolts. The bolts went all the way through the floor to the underneath of the motorhome. It took a lot of elbow grease, liquid wrench, and some tears but I finally got them loose. I filled the holes with some heavy duty sealant. Good luck.