When a local improvement guarantee fund duly created in any district exceeds in amount of moneys held therein by ten percent (10%) of the total outstanding obligations thereby guaranteed, then the board may, by resolution, authorize the treasurer or appropriate official of said district to return and pay such said excess or any part thereof to the general fund of said district to return and pay from such said excess or any designated part thereof all or any part of local improvement district bonds of said district then issued and outstanding or to be issued. The passage of such resolution shall require the affirmative vote of at least two-thirds (2/3) of the full board.