Yahoo tab added to Safari how to delete

Hello, ClimbRunSki.

Thank you for using Apple Support Communities.

If you're using iCloud Tabs, you can close them by following the steps in this article: Set up and use iCloud Tabs

"Close a tab

Quitting Safari, putting your device to sleep, or turning off your device doesn't remove a tab from the list.

On your Mac

1. Open Safari.
2. Click the Tabs  button. Below the images of tabs open on your Mac, you see a list of open tabs from your other supported devices. 
3. Hover the pointer over the tab that you want to close, then click the Close  button that appears."

You can also check out this article: Close tabs in Safari on Mac

Cheers!