It shall be unlawful for any person, firm or corporation to place or maintain or to display upon, or in view of, any street any unofficial sign, signal or device which purports to be, or is, an imitation of, or which resembles an official traffic sign or signal, or which attempts to direct the movement of traffic, or which hides from view an official traffic sign or signal. Every such prohibitive sign, signal or device is hereby declared to be a public nuisance, and the police department is hereby empowered to remove the same, or to cause the same to be removed without notice. (Ord. 12.53)