Firefox’s Forget button combines recent-history cleanup with closing open tabs. Use it only when that combined action fits the task. It is a poor diagnostic experiment for one troublesome website because it removes evidence and interrupts unrelated browser work.

Decide what must remain available

Review open documents, forms and uploads before starting. Save needed content through its application and keep any legitimate reference links you still need in an appropriate place. If you are investigating a suspicious page, retain the necessary incident details privately before deleting the browser history that would help locate it.

Mozilla describes three time ranges: five minutes, two hours and 24 hours. Identify when the activity occurred and read the selected range carefully. A broad range can remove useful recent navigation beyond the particular page you had in mind.

Do not use a shared browser’s cleanup control without understanding whose work and history it affects. A named browser profile or operating-system account helps establish the scope, but the person using it still needs to review the active session.

Apply the intended action once

If Forget is not on the toolbar, Mozilla documents adding it through Customise Toolbar. Open the button, choose the intended period and read the confirmation before selecting the red Forget action.

Firefox clears the history and cookies for that period, closes open tabs and opens a new clean window. Mozilla warns that the deleted information cannot be recovered through this feature. Treat that warning as part of the decision, not as a message to click past.

Afterwards, confirm the expected new window appears and reopen only the work you deliberately preserved. Check any local downloaded files separately; this article does not treat Forget as a file-erasure tool or removal of records held by websites.

For future private browsing, choose the appropriate session mode before starting. For one-site troubleshooting, choose a scoped method suited to that site. Forget is useful when its specific recent-history and session-closure behaviour is exactly what you want.

Sources: Mozilla Support.