Masking tape consists of adhesive applied to one side of a backing paper. Over time, the adhesive dries, holding the tape fast to the surface on which it rests. It is possible to remove dried masking tape from the surface by pulling it off, but you may receive better results by reactivating the glue. You must take great care when removing dried masking tape from paper, to avoid also removing a layer of the paper.
Place the paper on a flat, hard surface. Place one sharp edge of a razor blade parallel to one end of the tape. Move the edge of the blade under the edge of the tape. Work the blade down the length of the tape to separate it from the paper. Do this slowly to avoid damaging the paper. Continue until the masking tape is off the paper.
Apply heat. Point a hair dryer to the dried strip of masking tape to reactivate the glue. Use your free hand to peel one edge of the tape up and begin to pull it off. Do this slowly to avoid pulling off a layer of the paper.
Dip a small portion of a cotton cloth in warm water and squeeze some of the moisture out. Rub this moist part of the cloth on the tape. Ensure that you do not to rub the paper as well to avoid damaging it. Peel off the tape slowly.