How to uninstall Firefox Nightly on Windows

Back up Firefox Nightly bookmarks and profiles, including any data not synchronized to an account.

This covers Firefox Nightly 160.2610.1516.0 installed for the current user with winget (MSIX, ARM64). No Firefox account was signed in.

Quit Firefox Nightly first. The main process this time was firefox.exe.

Uninstall it from Settings, Apps, or:

Get-AppxPackage Mozilla.MozillaFirefoxNightly | Remove-AppxPackage

Where the data is

Location	What it holds	What to do
`Local\Packages\Mozilla.MozillaFirefoxNightly_jag0gd4e3s9p2`	The package's own data	Removed this time
`%LOCALAPPDATA%\Mozilla\Firefox`	The local side of the Firefox profile	Still there. Remove it only if you do not need that configuration
`%APPDATA%\Mozilla\Firefox`	Profiles, bookmarks and sign-in data	Still there. Leave it while you still use Nightly or another Firefox

%ProgramData%\Mozilla-1de4eec8-1241-4177-a864-e594e8d1fb38 also holds files from other Mozilla products. Do not delete that folder as a whole.

Check

Get-AppxPackage Mozilla.MozillaFirefoxNightly
Test-Path "$env:APPDATA\Mozilla\Firefox"

No output from that query does not prove the entry is absent when errors are suppressed. Confirm a successful query or an explicit missing-target result; a listed entry means it remains.
True on the second means the profile folder is still there.

Mole listed the package data and removed it. It also listed both Firefox profile folders as personal data, left them unselected, and did not delete them.

What Mole lists

Location	Item	Default
`%LOCALAPPDATA%\Packages\Mozilla.MozillaFirefoxNightly_jag0gd4e3s9p2`	Package data, removed with the app	Goes with the app row
`%LOCALAPPDATA%\Mozilla\Firefox`	Personal data; back up before removal	Listed but not selected
`%APPDATA%\Mozilla\Firefox`	Personal data; back up before removal	Listed but not selected

Removing the MSIX also removed its package data and startup task. Two listed browser-profile folders stayed unselected and survived. Shared Mozilla telemetry files were kept; uninstalling Nightly is not removal of other Mozilla browsers.

These defaults assume Remove data and settings with apps is off. Explicit Select all or Also remove user data can include the listed personal-data rows. Check the selection before confirming. Selected files that Mole removes go to the Recycle Bin; selected registry entries are backed up before removal. The vendor uninstaller has its own deletion behavior.

What this test covered

Recorded on 2026-10-20: Firefox Nightly, version 160.2610.1516.0, per-user, Store, winget package Mozilla.Firefox.Nightly.MSIX. The evidence comes from an ARM64 Windows test environment and a development build of Mole. It does not certify the current downloadable package or removal of real signed-in accounts, synchronized data or production projects.

Vendor documentation. The paths and removal results above are observations from the Windows test unless explicitly attributed to the vendor.