California Code, Probate Code - PROB § 661

(a) Unless the creating instrument otherwise provides, a general or special power of appointment that is a discretionary power, whether testamentary or otherwise, may be released, either with or without consideration, by a written instrument signed by the powerholder and delivered as provided in subdivision (c).

(b) A releasable power may be released with respect to the whole or any part of the appointive property and may also be released in such manner as to reduce or limit the permissible appointees.  No partial release of a power shall be deemed to make imperative the remaining power that was not imperative before the release unless the instrument of release expressly so provides.  No release of a power that is not presently exercisable is permissible where the donor designated persons or a class to take in default of the powerholder's exercise of the power unless the release serves to benefit all persons designated as provided by the donor.

(c) A release shall be delivered as follows:

(d) A release of a power of appointment that affects real property or obligations secured by real property shall be acknowledged and proved, and may be certified and recorded, in like manner and with like effect as grants of real property, and all statutory provisions relating to the recordation or nonrecordation of conveyances of real property and to the effect thereof apply to a release with like effect, without regard to the date when the release was delivered, if at all, pursuant to subdivision (c).  Failure to deliver, pursuant to subdivision (c), a release that is recorded pursuant to this subdivision does not affect the validity of any transaction with respect to the real property or obligation secured thereby, and the general laws of this state on recording and its effect govern the transaction.

(e) This section does not impair the validity of a release made before July 1, 1970.