Cal. Bus. & Prof. Code § 21706

If a declaration in opposition to the lien sale, executed under penalty of perjury, is not received by the owner on or prior to the date specified in the notice of lien sale by certified mail, is not completed and signed by the occupant, if the occupant cannot be contacted or served at the address provided in the declaration, or if the occupant withdraws the declaration in opposition to the lien sale in writing, the owner may, subject to the provisions of Sections 21708 and 21709, sell the property upon complying with the requirements set forth in Section 21707.