Suggestions in a login drop-down menu that have a key icon in front are login suggestions that you need to remove in the Password Manager.

• https://support.mozilla.org/en-US/kb/password-manager-remember-delete-edit-logins

Suggestions in a drop-down menu without a key symbol are autocomplete saved form data. Suggestions without a key icon are part of autocomplete saved form data that you should be able to remove by selecting this item with the cursor Down key and pressing Delete (Mac: Shift+Delete).

• https://support.mozilla.org/en-US/kb/control-whether-firefox-automatically-fills-forms

The corrupted email, address does not respond to the DELETE command as suggested in the first paragraph nor can SEARCH find it as in the second paragraph. What other option do I have ?

Make sure you use the cursor Down key to select/highlight this autocomplete item in the drop-down list,