Anyone know how to safely remove a previous coat off roof?

Please excuse my total and complete lack of knowledge. I'm not sure what you mean by "coach". It's an 88 Toyota Seabreeze 900, does that help? It seems like the front of the ("cab over?") and the first two feet of the roof are metal. Then there's a seam and it turns to fiberglass. Someone tried to patch a few spots and I'm not sure what it is. It almost looks like it has some type of super thin black fabric underneath when I peel it off.