Sec. 7. (a) A director may resign at any time by delivering written notice:
(1) to the board of directors, its chairman, or the secretary of the corporation; or
(2) if the articles of incorporation or bylaws so provide, to another designated officer.
(b) A resignation is effective when the notice is delivered unless the notice specifies:
(1) a later effective date; or
(2) an effective date determined upon the happening of an event.
(c) A resignation that is conditioned upon failing to receive a specified vote for election as a director may provide that the resignation is irrevocable.