Last I checked, question topics were closed when the moderator felt there was a need, not at request.
That, and it's extremely frowned upon (as in: DON'T DO THAT!) to go deleting all your posts in a question topic. The information may not only be your concern, but may provide useful information to someone else. This topic could provide insight for someone else who would ask a similar question. Clearing it after the fact messes all that up.
Which means slash-and-burn of a topic just because it has become unflattering to you is not the way to go.