When a "Local Improvement Guarantee Fund" duly created in any municipality exceeds in amount of moneys held therein ten per cent (10%) of the total outstanding obligations thereby guaranteed, then the council, may, by ordinance, authorize the treasurer or appropriate official of said municipality to return and pay such said excess or any part thereof to the general fund of said municipality to return and pay such said excess or any designated part thereof all or any part of local improvement district bonds of said municipality then issued and outstanding or to be issued. The passage of such ordinance shall require the affirmative vote of at least three-fourths (3/4) of the full council.