Mo. Rev. Stat. § 461.033: Revocation or change of beneficiaries designation.

1. A beneficiary designation may be revoked or changed in whole or in part during the lifetime of the owner. A revocation or change of a beneficiary designation involving property of joint owners may only be made with the agreement of all owners then living.

2. A subsequent beneficiary designation revokes a prior beneficiary designation unless the subsequent beneficiary designation expressly provides otherwise.

3. A revocation or change in a beneficiary designation shall comply with the terms of the governing instrument, the rules of the transferring entity and the applicable law.

4. A beneficiary designation may not be revoked or changed by the provisions of a will unless the beneficiary designation expressly grants the owner the right to revoke or change a beneficiary designation by will.

5. A transfer during the owner's lifetime of the owner's interest in property, with or without consideration, terminates the beneficiary designation with respect to the property transferred.

6. The effective date of a revocation or change in a beneficiary designation shall be determined in the same manner as the effective date of a beneficiary designation.