An elected city office is vacated under the following conditions. The Council shall declare an elective office vacant when the person elected:
(a) Fails to qualify or take office within 30 days after his election or appointment; or
(b) Is physically absent from the city for a 90-day period, unless excused by Council; or
(c) Resigns and his resignation is accepted; or
(d) Is physically or mentally unable to perform the duties of his office; or
(e) Is removed from office; or
(f) Misses three consecutive regular meetings unless excused; or
(g) Is convicted of a felony or of an offense involving a violation of his oath of office.