California Code, Streets and Highways Code - SHC § 31920

Any protest or objection made pursuant to this chapter, or any signature to such objection or protest, may be withdrawn by a written withdrawal signed by the person or persons who signed the protest or objection or who affixed the signature to be withdrawn, and filed with the clerk at any time prior to the determination by the legislative body as to whether or not a majority protest exists.  Any protest, objection, or signature withdrawn shall not be counted in computing a majority protest.