Settings under Mailboxes
I have removed additional email address however it still shows under settings, mailboxes.
Thank you for reaching out. First, please try clearing your cookies, cache and history: https://help.yahoo.com/kb/sln27197.html
After that, use a desktop computer/laptop and go to mail.yahoo.com on a preferred browser and follow these steps:
1. Click the Settings icon Image of the Settings icon..
2. Click More Settings.
3. Click Mailboxes.
4. Select the account you’d like to disconnect.
5. Click Remove mailbox.
6. Click Remove mailbox again to confirm.
7. Click Save.