N.C. Gen. Stat. § 47C-2-115

A declarant may maintain sales offices, management offices, and models in units or on common elements in the condominium only if the declaration so provides and specifies the rights of a declarant with regard to the number, size, location, and relocation thereof. Any sales office, management office, or model not designated a unit by the declaration is a common element, and if a declarant ceases to be a unit owner, he 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. The provisions of this section are subject to the provisions of other State law and to local ordinances.