Vehicle registered before 2015
The security codes have only existed since early 2015. If your vehicle was registered before then and never re-registered since, they may be missing.
The check costs nothing and you reveal nothing during it.
How to tell
Look at the round seal on the number plate. If you can see a small silver or matt field on it, there is a code underneath and online deregistration is possible.
If the seal is smooth and printed all over, with no field, then there is no code. In that case only the counter route remains.

If the codes are missing
Then neither we nor any other provider can deregister your vehicle online. That is not a question of the provider but of the law: without the codes, § 24 FZV requires identification of the applicant.
Check it with us for free. If it turns out not to work, you pay nothing and we send you the address of your registration office.
Have it checked for free
The check costs nothing and you reveal nothing during it.
Check for free whether it works