A declaration may be revoked at any time by the declarant, without regard to the declarant's mental state or competency, by any of the following methods, effectively communicated by the declarant to the attending physician or other concerned health care provider:
(1) Written revocation by the declarant, dated and signed by the declarant.
(2) By oral statement or revocation made by the declarant to the attending physician. This revocation shall be made a part of the declarant's medical record by the attending physician.