The Mayor or any Councilman shall forfeit his office if he:
(a) lacks at any time during his term of office any qualification for the office prescribed by this Charter or by law;
(b) violates any express prohibition of this Charter;
(c) is finally convicted of a felony from which he has not been pardoned or otherwise released from the legal disability; or
(d) fails to attend three (3) consecutive regular Council meetings or six (6) Council meetings in any calendar year without being excused by the Council.