Have you ever wanted to remove a wrong username you typed in a webmail login screen with your Mozilla/Firefox browser or just what to remove it from your friends browser you just used ?
Unfortunately, only usernames that actually have a saved password show in the "saved password" option menu.
So this is a quick "how to" delete a username from a login screen when using Firefox:
1. Go to the website that has the username that you wish to delete.
2. Type de first letter of the username
3. When you see it pop up in the dropdown menu under the username field (as seen in the first image on this page), simply make sure the username that you wish is highlighted by rolling over with your mouse
4. With the name selected highlighted let the mouse rest and hit the SHIFT+DELETE
it's that simple.