Are you just going to put down more indoor/outdoor carpeting? Or were you planning something that needs a nice smooth surface to adhere? Is the surface you are trying to get the glue off of plywood, linoleum, hardwood, cement, or what? When the previous carpet was down, could you either see or feel uneven places in it because of the glue? If not, and you plan to put down more carpet, you always have the option of just leaving it, and putting your new carpet over it. If your surface is plywood, you could try removing a THIN layer off the top, or you could put another thin layer over the top. Others will probably be along soon with some chemical solutions for you.