Within 60 days after vacation of a tenant or for signs lacking advertisement for a period of 60 days or more, any on-premises nonconforming sign shall be removed or brought into compliance by the property owner. If removal does not occur voluntarily, after appropriate notice, as specified in Section 11-3-102(3), the entire sign and support structure shall be taken down by the owner or may be removed by the City and all costs incurred shall be the responsibility of the property owner.