My first thought was also, what kind of glue? If its school glue or similar, soak the area in water. Keep dabbing with paper towel until the glue is gone. If its hot glue sticks, heat up the glue gun, swipe over the glue, remove excess glue with paper towels and small putty knife. Keep touching the glue until just the 'wet' spot remains. Place a paper towel over it and iron. Place a clean section of the paper towel over remaining spot and iron again. If its super glue, dab a cotton tip swab with diluted Goof Off and swipe the glue until soft and scrape it off. You will need to take soap and water and get the cleaner out of the pads fabric.
There is also a product called Un-Do Adhesive Remover at JoAnns.
Or, you could recover the pad with muslin and add the glue mistake to the list of things not to do again.