A sign shall be removed by the owner or lessee of the premises upon which the sign is located when the business which it advertises is no longer conducted on the premises. If the owner or lessee fails to remove it, the Building Commissioner shall give the owner 30 days' written notice by certified mail to remove it. Upon failure to comply with this notice, the Building Commissioner or his duly authorized representative may remove the sign at cost to the owner. Where a successor to a defunct business agrees to maintain the sign as provided in this Outdoor Advertising Sign Code, this removal requirement shall not apply. The new sign user shall forthwith notify the Building Commissioner's office, in writing, of this change. No new sign permit is required, unless the sign is altered or relocated. The Building Commissioner shall be notified in any matters relating to sign relocations.