Cal. HSC § 25166

(a) A person who is registered as a hazardous waste transporter may voluntarily surrender a registration by submitting a letter signed and dated by the registered hazardous waste transporter indicating that the transporter no longer wishes to transport hazardous waste. (b) A person whose registration has expired for a period of more than 90 days shall be considered an applicant for an original registration when the person applies for registration.