The moderators do, the ones with that neat little red bubble to be specific. And you can use the "contact us" link at the bottom of the page to talk to the admin of the site about a question you don't feel should have been removed.
HOWEVER, contrary to what DRE says all questions are removed for a reason. When you become a moderator they send you a whole list of things to look out for and delete when you see. We do encourage intellectual and healthy discussion but arguing, hating and trolling are not permitted. There are quite a few questions I've had to remove because they've been rude or offensive.
And no, offensive does not mean questioning the existence of a god, it means bashing the people who believe in him. Questions that don't make sense, questions that post names of people, phone numbers or talks about other members are not allowed, offensive questions are not allowed, advertisements for other sites aren't allowed, duplicate questions, questions where the asker reveals themselves to be under sixteen, explicitly sexual questions, and questions that are of inappropriate adult topics are all removed.
If you have a question about why a question was removed you can feel free to contact the admin and ask about it!
Mods/administration don't always remove according to their rules. A lot of it is discrimination, arbritrary and personal vendettas, resulting in Nazi abuse. That's being my case for the most part. Also, if so much as one person here doesn't like you, he/she can create multiple accounts and use it to flag your comments/questions repeatedly so it piles up on the reported list, making admin think this person is a multiple offender, thus makes her a target, after which mods stalk her. You'd think GAG authorities here wouldn't fall for such ploys, well think again.
Don't believe me? Well stay here long enough and you'll learn that truth for yourself. I once had issues with an infamous user here who's name I won't display. I did what I could to get rid of that person, yet in turn it got me in trouble. Though in the end, that user was permanently banned for violently threatening others. So I don't bother helping admin around here since they often takes sides with the bad guys.
The Supermods and Admin remove all questions.You should have received an email with a general explanation as to why your posting was removed. If you would like further details, please forward the email that we sent to you, and we will provide you with specific information regarding the decision to remove the posting. Thanks! :)