Drop down list of email addresses

This question has to do with logging into web sites with an email and a password. Firefox 101.0.1 (64-bit). Windows 10. On many sites, when I click in the email field, a drop down list of email addresses appears from which I can make a selection using the mouse or up/down arrow keys. Some web sites have as few as two email addresses in the drop down list, others have many more. I recall that one site has about fifteen email addresses in the drop down list. How can I remove a non-applicable email address from the drop down list? How can I clear the drop down list of all email addresses? Thanks.