The process for setting up advance directives was detailed earlier on this blog. Yet the very principle of advance directives is based on the assumption that your opinions do not change. When admitting you for treatment, your healthcare providers must assume that the manner of care that you requested in your advance directives still reflects your current wishes. What if they do not? Are you able to revoke them?
As you are the one who establishes your own advance directives, it is also your right to revoke them. Thus (as is stipulated in Section 4695 of California's Probate Code) you may at any time revoke all or part of your advance directives. You can do this in writing, by stating it either prior to or during the course of your care, or giving any indication that can implies an intent to revoke (such as shaking your head to the question of whether you want to revoke them). You must, however, demonstrate the capacity to comprehend your decision in order for the revocation to be valid.
If you have created written advance directive, you should know that a directive that appears to be contrary to an earlier one effectively revokes that prior directive. Keep in mind, too, that granting someone power of attorney for health care is similar to an advance directive, yet gives that person decision-making power.
Revoking the designation of an agent to whom you have given power of attorney for health care is somewhat different. That needs to be done either in writing or by personally informing the supervising healthcare provider of your intentions. If you designate your spouse as having power of attorney for health care in estate planning documents, only to later get a divorce, that designation is automatically revoked the moment your divorce becomes final.