Sign an old computer out of your Mozilla account

Firefox Sync can make bookmarks, passwords and history available across signed-in devices. When you sell, lose or stop using a computer, its Mozilla account connection deserves a review. Removing a connected service is distinct from wiping the computer or deleting every local browser item.

Before you start​

Use a device you still trust and sign in to the correct Mozilla account. Identify the retired computer by its displayed name and recent activity; duplicate connections can occur.

Do it step by step​

1. Open your Mozilla account from a known Firefox or Mozilla page and navigate to Connected Services.
2. Find the old computer or service. If more than one entry matches, inspect each before changing anything; Mozilla notes a device can appear more than once.
3. Select Sign out next to the connection you no longer need. Confirm the prompt and repeat only for other entries that truly belong to that device.
4. Review remaining connected services and secure the account with an updated password and second factor if the device was lost or you suspect another person accessed it.
5. If you still possess the computer, sign out locally too and follow a proper device reset before sale or handover. Check local Firefox data and operating-system accounts separately.

Check the result​

Refresh Connected Services and confirm the retired entry is absent. Test a current device to ensure you did not remove the wrong connection.

If something goes wrong​

A remote sign-out ends that account connection but is not proof that already synced data was erased from a lost or previously used machine. Treat a theft as a broader account and device incident.

Know the limit​

Mozilla distinguishes signing out a connected service from merely disabling Sync and explains that synced information can include passwords and browsing history. Mozilla's connected-device removal Mozilla's Firefox Sync sign-out guide