Article 3. Revocation Of Advance Directives of California Probate Code >> Division 4.7. >> Part 2. >> Chapter 1. >> Article 3.

(a) A patient having capacity may revoke the designation of an agent only by a signed writing or by personally informing the supervising health care provider.
  (b) A patient having capacity 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.

A health care provider, agent, conservator, or surrogate who is informed of a revocation of an advance health care directive shall promptly communicate the fact of the revocation to the supervising health care provider and to any health care institution where the patient is receiving care.

(a) If after executing a power of attorney for health care the principal's marriage to the agent is dissolved or annulled, the principal's designation of the former spouse as an agent to make health care decisions for the principal is revoked.
  (b) If the agent's authority is revoked solely by subdivision (a), it is revived by the principal's remarriage to the agent.

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