You can't delete questions on here unfortunately and moderators can only remove questions if they violate guidelines. Therefor it's best you contact the admin. Go onto your profile and just scroll down to the bottom of the page and select the "contact" option.
We don't remove questions or posts per user request, unless they violate the guidelines of the site. It's highly suggested that you make sure you're content with what you post, before you post it.
You can however "Disavow" your questions, which will make it anonymous, and you will receive no further notifications from said question. Also, if you happened to include a picture you no longer wish shown there and you linked from somewhere, you can delete/remove it from there, and it should also be unviewable here.