Do the same thing you'd do to remove gel or acrylic nails, with a shorter time frame. Oils your nails first, because this is pretty drying, then use a nail polish remover with acetone. Soak a cotton ball, slap it on your nail, wrap it in foil and wait about 3 - 5 minutes. The glitter will slide off with a little pressure, if it doesn't soak another 3 - 5 minutes and repeat.
Then for next time look at peel off base coats, like UNT that will just peel off in one piece with no remover, or check out glitter bases like Picture Polish's Glitter Base Coat that make removal of glitter much faster. Also, high end glitter polishes tend to remove better, and smaller glitter comes off more easily. So you may want to look at brand likes KB Shimmer or F.U.N Lacquer that have glitter formulas that remove more easily, or stick with microglitters and shimmers that come off faster than chunky glitters.