How to uninstall Thunderbird on Windows

Thunderbird keeps your messages, address books, saved passwords, filters and settings in a profile under %APPDATA%\Thunderbird, separate from the program. That is why you can remove and reinstall Thunderbird without losing mail, and also why the profile is the one thing to back up first: IMAP mail stays on the server, but local folders, address books and filters live only in the profile. This guide covers Thunderbird installed machine-wide from the Mozilla.Thunderbird winget package. Mozilla help: Thunderbird profiles

Back up the profile

In Thunderbird, open ≡ › Help › Troubleshooting Information. Next to Profile Folder, choose Open Folder.
Quit Thunderbird. Copy the whole profile folder (its name usually ends in default-release) to another disk or a folder outside %APPDATA%.

Quit Thunderbird first

Quit from the ≡ menu, not only by closing the window, then check Task Manager (Ctrl+Shift+Esc) for any thunderbird.exe still listed. Thunderbird runs several processes while open.

Remove the app with its own uninstaller

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

winget uninstall --id Mozilla.Thunderbird

Because it is installed for all users, Windows asks for administrator approval first. The profile stays on disk until you remove it yourself.

Where the data lives

Location	What it holds	What to do
`%ProgramFiles%\Mozilla Thunderbird`	Program files	The uninstaller removes it
`%APPDATA%\Thunderbird`	`profiles.ini` and your profiles: mail, address books, passwords, filters, settings	Back up first; keep it unless you are sure the backup opens
`%LOCALAPPDATA%\Thunderbird`	Disk cache for the profile	Safe to remove after Thunderbird has quit
`%APPDATA%\Mozilla\Thunderbird`	Empty on the test PC	Remove it if empty; leave the `Mozilla` parent, which Firefox shares
`HKCU\Software\Mozilla\Thunderbird`	Per-user settings	Remove for a clean start; leave `HKCU\Software\Mozilla` itself
`%ProgramData%\Mozilla-<id>`	An update lock and a small uninstall report	Safe to remove once Thunderbird is gone; other Mozilla apps may use similar folders

Check the result

Run these read-only commands after the uninstall finishes:

Get-Process thunderbird -ErrorAction SilentlyContinue
winget list --id Mozilla.Thunderbird
Test-Path "$env:ProgramFiles\Mozilla Thunderbird"
Get-ChildItem "$env:APPDATA\Thunderbird\Profiles" -ErrorAction SilentlyContinue

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 it is still running; quit it before copying or deleting the profile.
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 returning False means the program folder is gone.
Get-ChildItem listing a folder such as xxxxxxxx.default-release means the profile folder still exists; this does not verify the mail files inside it. An empty listing does not prove the profiles folder is gone; it may be empty or unreadable. Check the folder itself before deciding.

If you installed it with winget

winget uninstall runs the same uninstaller Settings › Apps uses; it does not touch %APPDATA%\Thunderbird.

Accounts

Thunderbird has no account of its own. Removing it does not touch your mail accounts with their providers.

What Mole lists

For Thunderbird installed machine-wide from winget:

The program folder and a row grouping Windows' own records of when you opened the program are selected by default.
%APPDATA%\Thunderbird, %LOCALAPPDATA%\Thunderbird and %APPDATA%\Mozilla\Thunderbird are shown as personal data: listed, never selected by default, and never ticked by "Also remove data".
The Start Menu and desktop shortcuts are listed but not selected.
HKCU\Software\Mozilla\Thunderbird is listed but not selected, and is backed up to a .reg file before removal if you tick it.
The %ProgramData%\Mozilla-<id> folder is not listed; check it and remove it yourself. Machine-wide registrations Thunderbird writes for all users are left alone.

What this test covered

Tested on September 28, 2026 with Thunderbird 156.0.1 installed through winget, machine scope, on an ARM64 test VM. Every listed row was ticked and removed in this test. No mail account was set up, so profile backup and restore were not verified end to end. The historical test tool's select-all included personal-data rows, so these removal results do not establish Mole's UI bulk-selection behavior.