It is easiest to remove the membrane if you can keep it intact. This means no sharp knives. However a blunt knife, like many kitchen knives or a butter knife (some people use a screwdriver). Slide the knife between the membrane and the bone gently. Work it around to loosen the membrane as much as possible. Once some of it has loosened, grab the membrane with a paper towel and start working it away from the meat and bones. Some racks will give up the membrane easily and others are difficult. You just have to work with it.