California Code, Vehicle Code - VEH § 21467

Every prohibited sign, signal, device, or light is a public nuisance, and the Department ofTransportation, members of the California Highway Patrol, and local authorities are hereby authorized and empowered without notice to remove the same, or cause the same to be removed, or the Director ofTransportation, the commissioner, or local authorities may bring an action as provided by law to abate such nuisance.