The city council shall have the right and power, in the exercise of a sound discretion, in the event that it shall determine that certain rules or provisions hereof should be amended or modified to protect or further the public interest or welfare, to amend or modify such rules or provisions from time to time; provided, that such amendments or modifications shall not be contrary to the public purpose expressed by this article. (Ord. 505 § 3. 2002 Code § 6-32.24).