C.R.S. § 15-15-213

(1) Rights at death under section 15-15-212 are determined by the type of account at the death of a party. The type of account may be altered by written notice given by a party to the financial institution to change the type of account or to stop or vary payment under the terms of the account. The notice must be signed by a party and received by the financial institution during the party’s lifetime. (2) A right of survivorship arising from the express terms of the account, section 15-15-212 , or a POD designation, may not be altered by will.