Every City officer shall take the oath of office prescribed by the Constitution of the State and shall file the same with the Clerk - Treasurer, together with any bond this Charter or the Council may require. Officers who refuse to comply with the provisions of this section within ten days after the beginning of a term of office or date of appointment shall be considered to have declined the office. The office shall then become vacant unless the Council extends the time in which the officer may qualify as required in this section.