CA Prob Code Section 4151

(a)

A principal may revoke a power of attorney as follows:

(1)

In accordance with the terms of the power of attorney.

(2)

By a writing. This paragraph is not subject to limitation in the power of attorney.

(b)

An attorney-in-fact or third person who does not have notice of the revocation is protected from liability as provided in Chapter 5 (commencing with Section 4300).