You don't, because you can't.
You can however create a second e-mail address for free: go to %26quot;Options%26quot; %26gt; %26quot;Accounts%26quot; and click on %26quot;Add or edit an account%26quot;. Read the text at the bottom of the page %26quot;Extra Mail Address%26quot; and click on %26quot;Get Started%26quot; to proceed.
Alternatively, you could also create a completely new account.
