Take a small piece of cotton ball, dip in polish remover, place on nail, wrap with tin foil.. do this to every nail and leave on for 2-5 mins, sometimes longer depending on the glitter polish. This works every time!
Soak a cotton ball in acetone and let it sit on your nails for a minute. That should loosen up the glitter and allow you to rub it off easily. My manicurist soaks the polish, then uses a buffer to help slough off any leftover pieces of glitter.