Nail polish remover (acetone I think)will "unstick" glued fingers so this might work. However, keep in mind that if your cell phone face is plastic (it probably is), the nail polish remover might permanently haze the clear lens. Try a cotton ball dipped in the polish remover on a scrap piece of plastic if you can find one and see if it gets hazy. Whatever you do, don't use an abrasive cloth to the lens.