If a nonconforming use is changed, it shall be changed to a use conforming to the regulations of the zone, and after it is changed, it shall not be changed back to a nonconforming use. If a use other than that allowed in the zone is desired, a change of zone may be applied for pursuant to Chapter 17.72 MMC (Applications and Review Process) and Chapter 17.74 MMC (Review Criteria). (Ord. 4128 (part), 1981; Ord. 3380 (part), 1968).