The council shall have the power to expel any of its members for violation of official duty, including gross neglect, and it may declare the seat of any member vacant by reason of disability to perform official duties. The council shall in such cases first, by resolution, direct the city attorney to draw up a bill of impeachment setting forth the charges and alleged conditions of disability, after which the council shall in special session try the charges, following in such trial the rules of courts of law as closely as possible. A vote of two-thirds of the members of the council shall be required to expel a member or vacate a member's seat. (Ord. 79-97 § 2 (part), 1979).