Here's the best way to remove finish nails from old woodwork. After carefully removing the woodwork from the wall, pull out the nails using a vise grip. Grasp the nail with the vice grip on the unfinished side of the wood and pull the nail through. Repeat this procedure until all the nails are removed. This method keeps the finished face of your woodwork intact.
Make sure to seal the top and bottom edges of all doors with a finish coat of paint or sealer to prevent moisture infiltration.