Though metal snap fasteners may appear to be embedded into a garment for eternity, you can remove them. Each side of the snap -- the top snap on one layer of fabric, the bottom snap on the second layer of fabric -- consists of two pieces fitted together with prongs. If you can separate the pronged piece from the rimmed piece holding it in place, you can remove the snap altogether. You must work carefully, though, so you do not tear any of the fabric while you work.
Lay the garment in front of you. Unfasten the snap. Remove each half of the snap separately.
Brace the portion of fabric around the snap by pulling the fabric taut with the fingers of the hand-holding the garment.
Hold the screwdriver in your dominant hand. Insert the head of screwdriver under the exterior portion of a snap. Of the two pieces that form each snap half, the interior portion -- the piece that snaps onto the other snap half -- is the rimmed piece. The exterior portion is the piece with prongs. The exterior portion probably appears as a small metal ring on the underside of the garment, or as a solid, covered button-shape on the top of the garment.
Whittle under the metal ring with the screwdriver, to pull the prongs up. Keep whittling carefully to pull the prongs off the rim of the other snap piece, and through the fabric.
Remove both pieces of the snap half, once you pull all the prongs free.
Repeat the process with the other half of the snap.