If the violation has not been corrected pursuant to the requirements set forth in the notice of violation, or, in the event of an appeal, within 15 days of the decision of the City Manager or designee, then representatives of the city may enter upon the subject private property and are authorized to take any measures necessary to abate the violation and/or restore the property. It shall be unlawful for any person, owner, agent, or person in possession of any premises to refuse to allow the city or designated city contractor to enter upon the premised for the purposes set forth above.