The VRM or registration number is the key to each vehicle record and cannot be amended, therefore you need to delete the incorrect record completely and then add the vehicle again, using the correct registration number.
To delete the incorrect record, use the find vehicle facility on the home page to locate the incorrect vehicle record. Click on the registration number link to view the update vehicle form.
Click the delete button at the bottom of the update vehicle form – a warning will be displayed and must be confirmed, since this facility will remove the record as if it never existed.
Then use the add new vehicle form to enter the correct details.