(1) Any advertising device which violates the provisions of this article is hereby declared to be a public nuisance and the department shall give sixty days’ notice, by certified or registered mail, to the owner of the advertising device and to the owner of the property on which such device is located to remove the device. Provided, however, that any sign, display, or device lawfully in existence along the highway on September 1, 1965, which is not in conformity with the provisions contained herein, shall not be required to be removed until July 1, 1971, except that the Department of Transportation may jointly agree with the owner of any sign or the property owner for the earlier removal of such sign. Any other sign, display, or device lawfully erected subsequent to September 1, 1965, and prior to June 11, 1969, which does not conform with the requirements of this article may not be required to be removed until the end of the fifth year after the erection thereof, or after it becomes nonconforming, except that the Department of Transportation may jointly agree with the owner of any sign, or the property owner, for the earlier removal of such sign.

(2) Employees or agents of the Department are hereby authorized to go upon the property upon which a prohibited or nonconforming device is located, after expiration of the sixty-day period, for the purpose of removing the advertising device. The period of such notice shall be computed from the date of mailing. No notice, however, shall be required to be given to the owner of an advertising sign, display, or device whose name is not stated thereon or on the structure on which it is displayed as required in § 57-25-630.