To remove an email address from your Yahoo! Groups account, the address must be removed from the Alternate Email Address section of your Yahoo! Account Information page. Remember that any groups you subscribed to using the address will no longer be accessible until the address is linked to a Yahoo! ID.
To change the Yahoo! ID that the email address is linked to, simply sign in with the correct Yahoo! ID and use the Membership Wizard to add the email address to your account.
Yahoo! Answers from fellow Groups users