Haw. Rev. Stat. § 327E-4: Revocation of advance health-care directive.

(a) An individual may revoke the designation of an agent only by a signed writing or by personally informing the supervising health-care provider.

(b) An individual may revoke all or part of an advance health-care directive, other than the designation of an agent, at any time and in any manner that communicates an intent to revoke.

(c) A health-care provider, agent, guardian, or surrogate who is informed of a revocation shall promptly communicate the fact of the revocation to the supervising health-care provider and to any health-care institution at which the patient is receiving care.

(d) A decree of annulment, divorce, dissolution of marriage, or legal separation revokes a previous designation of a spouse as agent unless otherwise specified in the decree or in a power of attorney for health care.

(e) An advance health-care directive that conflicts with an earlier advance health-care directive revokes the earlier directive to the extent of the conflict.