Ohio Revised Code Title XXI. Courts Probate Juvenile § 2133.04

(A) A declarant may revoke a declaration at any time and in any manner. The revocation shall be effective when the declarant expresses an intention to revoke the declaration, except that, if the declarant made the declarant's attending physician aware of the declaration, the revocation shall be effective upon its communication to the attending physician of the declarant by the declarant, a witness to the revocation, or other health care personnel to whom the revocation is communicated by that witness. Absent actual knowledge to the contrary, the attending physician of a declarant and other health care personnel who are informed of the revocation of a declaration by an alleged witness may rely on the information and act in accordance with the revocation.

(B) Upon the communication as described in division (A) of this section to the attending physician of a declarant of the fact that the declaration has been revoked, the attending physician or other health care personnel acting under the direction of the attending physician shall make the fact a part of the declarant's medical record.

(C) Unless a declaration provides otherwise, a declaration is revoked by a subsequent declaration.