You can use these steps to remove saved items from an autocomplete drop-down list.

1. click the (empty) input field on the web page to open the drop-down list
2. highlight an entry in the drop-down list with cursor Down key
   do not click the mouse or press the Enter key
3. press the Delete key (on Mac: Shift+Delete) to delete the highlighted entry

Note that hovering with the mouse no longer works.

Form fill can also cause such suggestions to appear. To see all History and Cookie settings, choose:

• Options/Preferences -> Privacy & Security
  Firefox will: "Use custom settings for history"
• https://support.mozilla.org/en-US/kb/firefox-options-preferences-and-settings

Thanks for your suggestion, but it did not work as I hoped it would. It did delete the undesired username, but only for that login. I logged in, deleted the username, and then logged out. But when I logged back in, my username reappeared when I left-clicked the username box. By the way, I had already selected "Use custom settings for history" in Options ->Preferences -> Privacy & Security.

Hello ronbar59,

Just to make sure - woud you check this please :

3-bar menu => Options => Privacy & Security => under 'Logins & Passwords' make sure that 'Ask to save logins and passwords for websites' is unchecked.

'Ask to save logins and passwords for websites' was checked. I unchecked it and closed FF. When I reopened FF I tried to login to the website with the problem. The Username didn't appear, so I entered it and logged in. Then I logged off and on again. The Username was still being displayed when I left-clicked in the box.

Would you try this please :

Type in the address bar about:config and press Enter (promise to be careful, if asked)

Type in the search bar and look for the preference :

signon.autofillForms

and make sure its value is set to false

If you have to change it, then close and restart Firefox.

I totally forgot to ask : do you use the Password Manager  ?

If so, would you take a look at this article :

https://support.mozilla.org/en-US/kb/password-manager-remember-delete-change-and-import

Thanks, McCoy, for your help and the suggestions. The preference : "signon.autofillForms" was set to 'true'. I used "toggle" to change it to 'false'; then closed and restarted Firefox. The problem remained as it was... and, Yes, I do use the Password Manager. I looked at that article again, but still found nothing there that helped me fix this. Thanks again, Ron

ronbar59 said

I had already selected "Use custom settings for history" in Options ->Preferences -> Privacy & Security.

Please forgive me if this is a rhetorical question, but : Did you make sure that 'Remember search and form history' is unchecked ?

Thanks for the reminder, McCoy. You have fixed it! No, I had not made sure that 'Remember search and form history' was unchecked. I looked again and found it was, in fact, checked. I unchecked it. Then I closed options, closed Firefox, reopened Firefox, and tried again. The problem has been fixed! Thanks again, McCoy.

I sure am glad that fixed it - I should have asked you that question earlier (would have saved you a lot of time and hassle ....).