Colo. Rev. Stat. § 31-4-402
In the event that the official bond of any officer of a city or town, after the taking and approval thereof, becomes insufficient by reason of the death or insolvency of any of the sureties thereon, the governing body of such city or town may require such officer to procure additional sureties or to give a new bond and may designate the time when such additional sureties or new bond shall be furnished, which shall not be less than ten days, or may waive the requirement for such sureties or new bond. In the event that the additional sureties or new bond is not furnished within the time so designated and the requirement for such sureties or new bond is not waived, the office shall be declared vacant, and the vacancy shall be filled by election or appointment as provided by law.
C.R.S. § 31-4-402
This section is similar to former § 31-5-302 as it existed prior to 1975.