You can’t delete your Click and Buy account, because, so they say, “you don’t have to”. LOL! Several of our users got into serious trouble with Clickandbuy because of hacked iTunes accounts, so they really should provide a decent account removal service.
You can read their official statement here:
In short: if you want to cancel your membership, just send an email to ser[email protected] indicating your customer number. You will then receive a confirmation of your cancellation via email. Hope this helps!