Colo. Rev. Stat. § 4-4-403
loss. (a) A customer or any person authorized to draw on the account if there is more than one person may stop payment of any item drawn on the customer's account or close the account by an order to the bank describing the item or account with reasonable certainty received at a time and in a manner that affords the bank a reasonable opportunity to act on it before any action by the bank with respect to the item described in section 4-4-303. If the signature of more than one person is required to draw on an account, any of these persons may stop payment or close the account.
Source: L. 94: Entire article amended with relocations, p. 900, § 2, effective January 1, 1995.