A Contact List is deleted by issuing an HTTP DELETE to the entry's URI. The call will return 204 No Content if it succeeds.
This is simple an HTTP DELETE Request (which is set differently depending on the language you are coding in) to the List URI. There is no required content so the request itself is virtually identical to a GET. The only difference is to make sure you set the request type to DELETE.
Dave Berard Senior Product Manager, Constant Contact