A nonconforming use of a building, other structure or land or part thereof, may be changed to a use of the same or of a more restricted character, but may not thereafter be changed to any less restricted use, more intensive or lower class of use.
No part of any building, other structure or land occupied by a nonconforming use which is changed to or replaced by a use conforming to the provisions of this zoning title shall thereafter be used or occupied for a nonconforming use. Once changed to a conforming use, no such building, other structure or land shall be permitted to revert to a nonconforming use. A nonconforming use shall not be substituted or added to another nonconforming use. (1983 Code)