Take an old spoon and scrape away as much as you can. Vacuum the loose pieces. Put some ice in a bag and rub the gum until it is frozen. Then chip away at the gum with the spoon. Vacuum area again. Dab with a small amount of dry cleaning fluid, which should remove anything that may be left. Blot on detergent solution of 1/4 tsp mild dish-washing liquid and 1 cup warm water. Rinse.
That should get rid of it.