Firefox on Windows, Mac, and Linux keeps track of everything you download in its Library—unless you were using Private Browsing mode and just closed it. To erase your tracks otherwise, you’ll need to do it manually. Here’s how.
First, open Firefox. In any Firefox window, click the menu button (three lines) and select “Downloads.” Or you can press Ctrl+J (Command+J on Mac) on your keyboard.
The Firefox “Library” window will open, focused on your “Downloads” history in the sidebar on the left. You’ll see a list of downloads in progress or completed, and you can perform several actions here, such as clicking the small folder icon beside any entry in the list to see the downloaded file’s current location.
To remove a single downloaded file from your Downloads history, right-click its entry in the list and select “Remove From History” in the short menu that appears. This will not delete the file that is stored on your computer.
To clear your entire Firefox download history in the Library > Downloads window, click the “Clear Downloads” button on the toolbar.
Warning: Clearing your download history in Firefox won’t affect or delete the files you’ve saved to your device. If you want to delete the files themselves, you’ll need to find their download locations and delete them manually.
After clicking “Clear Downloads,” your download history will disappear, and you can safely close the Library window.
Firefox’s Private mode does temporarily record your download history while you’re still using Private mode, but once you close all Private windows, your download history will be erased automatically.
Just remember that the downloaded files won’t be erased automatically: Firefox will forget it downloaded them, but you’ll have to delete them from your computer’s storage manually if you don’t want them laying around.