Any lawful nonconforming use of a building or land may be changed to another nonconforming use of the same classification, which shall thereafter not be subject to any further change except to a conforming use, and for such purpose, a building may be extended in accordance with Section 17.72.020. Wherever a nonconforming use or a building or a land has been changed to a conforming use, such conforming use shall not thereafter be changed to a nonconforming use.
(Ord. 81-11 Art. XVI § 4, 1980).