The maintenance of the parking and loading spaces required shall be a continuing obligation of the owner of the real estate upon which the building or structure is located as long as the building or structure exists and the use requiring such space continues. It shall be unlawful for an owner of a building or structure affected by these requirements to discontinue, change or dispense with or to cause the discontinuance, sale or transfer of such building or structure, without establishing alternative spaces which conform to those requirements; or for any person, firm, or corporation to use such building or structure without providing such required parking or loading spaces, in compliance with these regulations. (Prior gen. code § 8-63.1)