To remove rust from screws, spray the screws with some liquid penetrant. Allow it to work for at least fifteen minutes before going on. Dip a screw driver in some valve lapping compound to give it more traction and bite on the screw head. Using a cigar lighting torch, heat the material on which the screw is stuck. Set the screw driver into the screw and hit its back using a hammer to loosen the screw and knock off the rust.