Whenever there exists within the corporate limits of the City of Freeport any territory not suitable or necessary for City purposes, the City Council may, upon a petition signed by a majority of the qualified voters residing in such territory if the same be inhabited, or without any such petition if the same be uninhabited, by ordinance duly passed, discontinue said territory as part of said City; said petition and ordinance shall specify accurately the metes and bounds of the territory sought to be eliminated from the City and shall contain a plat designating such territory so that the same can be definitely ascertained; and when said ordinance has been duly passed  the  same  shall be  entered  upon the minutes and records of said City, and from and after the entry of such ordinance said territory shall cease to be a part of said City, but said territory shall still be liable for its pro rata share of any debts incurred while said area was a part of said City, and the City shall continue to levy, assess and collect taxes on the property within said territory to pay the indebtedness incurred while said area was a part of the City as though the same had not been excluded from the boundaries of the City.