Maryland Health - General Section 5-604

      (a)      An advance directive may be revoked at any time by a declarant by a signed and dated writing, by physical cancellation or destruction, by an oral statement to a health care practitioner or by the execution of a subsequent directive.

      (b)      If a declarant revokes an advance directive by an oral statement to a health care practitioner, the practitioner and a witness to the oral revocation shall document the substance of the oral revocation in the declarant's medical record.

      (c)      It shall be the responsibility of the declarant, to the extent reasonably possible, to notify any person to whom the declarant has provided a copy of the directive.