Take your time, write clearly, and mail it certified so you have proof they received it.
The California DMV is a bureaucracy. It runs on paper. If you made a mistake (a false fact), the system cannot read your mind. To unwind the error, you must feed the system a correction—the ca dmv unwind statement of facts
Go to the DMV website and search for REG 256 . Do not use an old version—DMV updates these regularly. Take your time, write clearly, and mail it
The Solution: You file a new REG 256 to "unwind" your promise. You check "Planned Non-Operation (PNO)" or "Sale of Vehicle." You state: "I am unwinding my previous commitment to smog this vehicle. The vehicle is not operational and is currently stored in my garage. I request Non-Operational status effective immediately." If you made a mistake (a false fact),