To remove unaccepted friends requests you sent in facebook, go to that person's timeline whom you made request and then find the "Friend request sent' button on the top of the page and click on 'Cancel request' button in the dropdown menu. Simple.
Keep this in mind that Facebook is not a place to show 'how huge your friend list is'. If you request people you don't know personally or indirectly, then you shouldn't do it because it can bring you in in the facebook blacklist. They can delete your account and if you again try to make another account, then its most possible that they can deny it due to your same IP address.