How can I change my e mail address?
Email addresses cannot be changed. You have to sign up for a new one. Sign out of your existing account and then sign up for a new Yahoo account here: https://help.yahoo.com/kb/mail-for-desktop/sln2056.html
You can't. You have to get a new email address; https://login.yahoo.com/account/create?.lang=en-US&.intl=us&.src=yhelp