A declarant may maintain sales offices, management offices, and models in units or on common elements in the cooperative only if the declaration so provides and specifies the rights of a declarant with regard to the number, size, location, and relocation of such offices or models. Any sales office, management office, or model not designated a unit by the declaration is a common element, and if a declarant ceases to have an ownership interest in the association, he ceases to have any rights with regard to such offices or models, unless it is removed promptly from the cooperative in accordance with a right to remove reserved in the declaration. Subject to any limitations in the declaration, a declarant may maintain signs on the common elements advertising the cooperative. The provisions of this section are subject to the provisions of other state law and to local ordinances.