Iowa Code § 144C.7: Revocation of declaration.

1. A declaration is revocable by a declarant in a writing signed and dated by the declarant.

2. Unless otherwise expressly provided in a declaration:

a. A dissolution of marriage, annulment of marriage, or legal separation between the declarant and the declarant’s spouse that occurs subsequent to the execution of the declaration constitutes an automatic revocation of the spouse as a designee.

b. A designation of a person as a designee pursuant to a declaration is ineffective if the designation is revoked by the declarant in writing subsequent to the execution of the declaration or if the designee is unable or unwilling to serve as the designee.