rubber edpm roof completely seperated loose

If it's not leaking, my first thought would be to locate where the air is getting under it and seal that area only. If you can eliminate the entry point for the air pocket you should not have to worry about the rest of the roof. Check the front cap area if it's starting there. You might need to unscrew the trim and reposition the rubber and glue it as far back from there then replace the trim and reseal with dicor self leveling caulk over all the screws and trim.

A quick fix may be as simple as applying some eternabond down the area where you suspect the entry point of the air.

If it were mine I would not attempt to cut the membrane as a fix.