(a) A City office shall become vacant upon the occurrence of any of the following events:
(1) Expiration of the term of office;
(2) Death of the incumbent;
(3) Resignation;
(4) Removal from office;
(5) Ceasing to possess the qualifications or eligibility required by this Charter for election or appointment to office, subject to subsection (b) of this section;
(6) Conviction of a felony crime or of an offense involving a violation of an oath of office;
(7) A decision of a competent tribunal declaring the officer's election or appointment void;
(8) Failure to take the oath or file or have furnished for him the bond required for the office within ten days from the date of election or appointment or within such other time, not exceeding twenty days thereafter, as the Council may fix;
(9) In the case of Councilmen, absence from four consecutive regular meetings of the Council, unless such absences be excused by the Council at the time they occur or at or prior to the fourth such absence, or absence from twenty-five percent of such meetings in any year, unless such absences shall be excused;
(10) Absence from the City or failure to perform the duties of his office for sixty consecutive days, unless such absence from the City or failure to perform the duties of such office shall be excused by the Council prior to the expiration of such sixty-day period; or
(11) Any other event which, by law, creates a vacancy.
(b) No person who is in default to the City shall continue thereafter to hold any City office, unless he shall eliminate the same within thirty days after notice thereof is filed with the Clerk by the Attorney and a copy thereof is served on him. However, when an officer contests an alleged default by recognized means of legal procedure, brought prior to or within thirty days after notice is served on him, such thirty-day period shall not commence until a determination has been made by the court or tribunal in which the evidence of the default is contested.