Vacancies shall be declared in the office of a Trustee by the Board when the Trustee declines or is unable to serve, or is absent without cause from all regular Board meetings for a period of one year, or is convicted of a misdemeanor for failing, neglecting or refusing to discharge any duty imposed upon a Trustee or becomes a nonresident of the city, or who fails to pay the library taxes levied by the corporate authorities.
(75 ILCS 5/4-4) (1999 Code, § 20-1-4)