Yes u can but u have to wait 90days and hope that someone else does not book it before you do.First you need to delete extra email. Then delete that Yahoo alias (Account Info page)If your ID is old then yahoo will delete it but will not let anyone else use the same ID again for 90days (for security reasons).So in other words, after deleting ID, you will have to wait for 90days. And then re-register that as a NEW id.PS: based on what i did 3-4 yrs back. Dont know if policy is same now.