I have a delta 88 royal convertible, front disc brakes, rear drum brakes

I developed a big leak in my brake line going to the rear. I got the proportioning valve off, and the line that goes through the rear frame to the rubber line that goes to the top of the differential and then to the wheels, how could I get that off? I am having a hard time. I am replacing the line from the front block to the rear, the lines above the differential were replaced it seems, they look new anyways, i will be doing the front lines and that too, but i need to get it driveable to storage for the winter. any ideas?