The boundaries of any city in this state may be altered and a portion of the territory thereof excluded therefrom, and the councils of such cities are hereby granted power to enact ordinances for that purpose. Such alteration shall not relieve any territory excluded from the limits of a city from its liability on account of any outstanding bonded or other indebtedness of such city or of any bonded or other indebtedness of any improvement district of which the excluded territory is an existing part at the time of the passage of such ordinance. For the purpose of collecting any of the indebtedness specified in this section, the territory so excluded shall be and remain under the jurisdiction of such city. Immediately after the passage, approval and publication of said ordinance, a copy thereof duly certified by the clerk of said city shall be filed in compliance with the provisions of section 63-215, Idaho Code. Thereafter, the boundaries of said city shall be as set forth in said ordinance.