How to uninstall Firefox on Windows

Firefox can sync bookmarks, history, passwords and add-ons to your Mozilla account, but a profile that has never synced, or a saved password you have not exported, exists only on this PC. Check your sync status and export anything you need before you remove Firefox. Removing the app and removing your browsing data are separate decisions. This guide covers Firefox installed machine-wide from the Mozilla.Firefox winget package.

Quit Firefox first

Firefox runs one process per tab group plus helpers, so close every window from its own menu, then check Task Manager (Ctrl+Shift+Esc) for any firefox process still listed before you uninstall.

Remove the app with its own uninstaller

Go to Settings › Apps › Installed apps, find Mozilla Firefox, and choose Uninstall, or run:

winget uninstall --id Mozilla.Firefox

Where the data lives

Location	What it holds	What to do
`%APPDATA%\Mozilla\Firefox`	Your profile: bookmarks, history, saved passwords, extensions	Personal data. Copy and verify it first if you want to keep it, or leave it if you plan to reinstall
`%LOCALAPPDATA%\Mozilla\Firefox`	Disk cache and other per-profile temporary data	Personal data. Safe to remove once you no longer need Firefox on this PC
`HKCU\SOFTWARE\Mozilla\Firefox`	Firefox's own registry values	Safe to remove

Check the result

Run these read-only commands after the uninstall finishes:

Get-Process firefox -ErrorAction SilentlyContinue
winget list --id Mozilla.Firefox
Test-Path "$env:ProgramFiles\Mozilla Firefox"
Test-Path "$env:APPDATA\Mozilla\Firefox"

No output from Get-Process only means this query observed no matching process; a suppressed error leaves the running state unknown. A listed process means a window or helper is still open.
A completed winget list query with no match means the package record is gone; a matching row means the uninstall did not finish.
Test-Path "$env:ProgramFiles\Mozilla Firefox" returning False means the program folder is gone; True means files remain there.
Test-Path "$env:APPDATA\Mozilla\Firefox" returning True means your profile is still there, which is expected unless you removed it yourself.

If you installed it with winget

winget uninstall runs the same uninstaller Settings › Apps uses and removes the same program files; it does not touch your profile in %APPDATA%\Mozilla\Firefox or the cache in %LOCALAPPDATA%\Mozilla\Firefox on its own.

Account and sync

Uninstalling Firefox does not sign you out of your Mozilla account or remove data already synced to it. If your bookmarks and passwords are fully synced, reinstalling and signing in restores them without needing the local profile folder above.

What Mole lists

For Firefox installed machine-wide from winget:

The program folder and every shortcut are selected by default.
%APPDATA%\Mozilla\Firefox and %LOCALAPPDATA%\Mozilla\Firefox, your profile and its cache, are listed as personal data: never selected and never ticked by a bulk action; tick them yourself if you want them gone.
HKCU\SOFTWARE\Mozilla\Firefox is listed but not selected.

What this test covered

Tested with Firefox 156.0.1 installed through winget, machine scope, and removed by selecting every item Mole listed, including the personal-data rows. Firefox was not signed in and sync was not exercised, so restoring synced data after removal was not tested. The historical test tool's select-all included personal-data rows, so these removal results do not establish Mole's UI bulk-selection behavior.