321.556.  Repeal of sales tax, procedure, exceptions — ballot language. — 1.  The governing body of any ambulance or fire protection district, when presented with a petition signed by at least twenty percent of the registered voters in the ambulance or fire protection district that voted in the last gubernatorial election, calling for an election to repeal the tax pursuant to section 321.552, shall submit the question to the voters using the same procedure by which the imposition of the tax was voted.  The ballot of submission shall be in substantially the following form:

  2.  If a majority of the votes cast on the proposal by the qualified voters of the district voting thereon are in favor of repeal, that repeal shall become effective December thirty-first of the calendar year in which such repeal was approved.