Is it still stuck up there real good? If so, leave it alone. That's one of those "just because" jobs that's usually not worth doing. Also consider this, that's sheet metal which shows to the outside. It's not a heavy floor or inner brace. Any excess digging and you'll see drag marks in the painted surface. It will dent easily too so inner roof surfaces don't suffer that kind of work very well. If you have thin layers hanging here n there just pull em down and leave the rest. It's been stuck up there since it was built so why take it down?
Since we're talking about that area this is a good time to mention that each wire (headliner lanyards) has a specific place. It's always prudent to number or letter each one as it gets removed or the headliner replacement will be hell. Like A,B,C, from front to back or 1, 2, 3. Some guys leave them in the headliner and wrap it up too marking the front.