Askbot supports deleting a question but keeps a record of it. In particular, it shows the deleted questions one has asked in the profile and you can hover over and even get a preview. I think it shouldn't show a preview for deleted questions. I would also like a option to "hard delete" or destroy the record of the question ever been asked. This is useful in some extreme circumstances.
Destroying a user instead of merely suspending or blocking would also be useful. If a user is just deleted, their records of past activity should still exist but if a user is destroyed, all questions/answers/comments by the user should be removed along with the record of the user