How can I delete AutoComplete history in Mozilla Firefox? To delete AutoComplete history in Mozilla Firefox: • Select "Tools" • Select "Options". • Open the "Privacy" tab. • Click the "Clear" button in the "Saved Form Information" area.
If you don't want Firefox to save this data in the future, remove the check mark from the "Save information I enter in web page forms and the Search Bar". Also see How disable AutoComplete forms in Mozilla Firefox