Sec. 6-11   Declaration of vacancy in office; causes enumerated
   If any person elected to office shall die, resign, move from the city, be removed from office, or be convicted of a felony, or if any councilperson or mayor shall absent himself from council meetings for a period of five unexcused consecutive regular meetings or ten unexcused regular meetings within a year without good and sufficient reason, and without the permission of the council, the office held by such person shall be deemed to be vacant.