California Code, Revenue and Taxation Code - RTC § 38525

(a) If the board determines that the amount of tax, interest, and penalties are sufficiently secured by a lien or other property or that the release or subordination of the lien imposed under this article will not jeopardize the collection of the amount of the tax, interest, and penalties, the board may at any time release all or any portion of the property subject to the lien from the lien or may subordinate the lien to other liens and encumbrances.

(b) If the board finds that the liability represented by the lien imposed under this article, including any interest accrued thereon, is legally unenforceable, the board may release the lien.

(c) A certificate by the board to the effect that any property has been released from a lien or that the lien has been subordinated to other liens and encumbrances is conclusive evidence that the property has been released or that the lien has been subordinated as provided in the certificate.