If the declaration so provides and specifies the rights of a declarant with regard to their number, size, location and relocation, a declarant may maintain sales offices, management offices, and models in the condominium. Any sales office, management office, or model not designated a unit by the declaration is a common element, and a declarant ceasing to be a unit owner, ceases to have any rights with regard thereto unless it is removed promptly from the condominium 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 condominium.