If it's regular Elmer's glue, soaking it in cold water should do the trick. Elmer's is water-based, so it's simply a matter of dissolving the adhesive. The glitter should come out when the glue is dissolved. Change the water when it becomes cloudy. When the water stays clear and the spot appears clean, launder the skirt as usual.
The best way to remove Elmer's glue from an expensive cotton skirt rubbing it off using a small amount of slightly-heated vinegar. Be sure to allow the vinegar to soak for at least a half an hour before wiping it clean. The glitter can be removed by spraying the skirt with regular aerosol hairspray then rub it off after the hairspray has dried off.