Signs pertaining to enterprises or occupants that are no longer using a property shall be removed from the premises or sign copy on such signs shall be obliterated, within thirty days after the associated enterprise or occupant has vacated the premises. Other signs of a temporary nature (including political signs) shall be removed within fifteen days following the event or ejection or other purpose served by the sign in the first instance. (Prior gen. code § 8-60.65.2)