Notwithstanding anything contained in these sign regulations or this Code to the contrary, any sign erected pursuant to the provisions of these sign regulations or this Code with a commercial message may, at the option of the owner, contain a noncommercial message unrelated to the business located on the premises where the sign is erected. The noncommercial message may occupy the entire sign face or any portion thereof. The sign face may be changed from a commercial to a noncommercial message, or from one noncommercial message to another, as frequently as desired by the owner of the sign, provided that the sign is not a prohibited sign or sign-type and provided that the size, height, setback and other dimensional criteria contained in these sign regulations and this Code have been satisfied.