How can i delete a question i posted in here?

if a best answer hasn't been picked for it just go back to the question hover over it and click delete and poof question gone

If the question has answers, the only real way to remove them is as violations. You will need to get friends and network to report. The easiest thing to do is go to the question and change the asker to anonymous. You will then be the only one who knows it is you. The staff in the past would remove one or two, but no longer.

You can delete your own question if there is no answer. Once your question has been answered the delete option under the blue edit tab is removed. So now the question cannot be deleted. At the point the question is answered it now becomes the property of Yahoo Search and cannot be removed except for a violation. It can be reported and removed or you could always make your question anonymous. That way at least anyone who sees your question in the future will not know it's you.