cornfieldlabs

Mac: Getting rid of an old Microsoft Teams account that keeps coming back

I had an old work account stuck in Microsoft Teams on my Mac. Signing out didn’t help. Deleting things didn’t help either: every time I relaunched Teams, the account was back, like nothing happened.

It took a fair bit of digging, so here’s what I found, in case you’re stuck in the same loop.

Where Teams keeps your account

The new Teams client uses Microsoft’s OneAuth for single sign-on, and OneAuth keeps account details and refresh tokens in the macOS Keychain.

You can look for it with the security command. I found an entry with the service name OneAuthAccount, and its account name was a UUID. The entry also had a hex-encoded attribute (gena). Decoding that hex gave me a small JSON blob with the account’s profile:

• Login name (the old work email)
• Display name
• Account ID (a UUID, <account-id> from here on)
• Tenant ID (another UUID, <tenant-id> from here on)

Those two IDs turned out to be the useful bit. Once you have them, you can search for them on disk.

Where the cache files live

OneAuth’s shared store

~/Library/Group Containers/UBF8T346G9.com.microsoft.oneauth/BlobStore/

This folder had files named straight after the IDs:

• <account-id>_graph_organization_metadata (account info)
• <account-id>_avatar_metadata (profile picture)
• <tenant-id>_hrd (home realm discovery for the old organization)

Teams’ own sandboxed containers

• ~/Library/Containers/com.microsoft.teams2/ (the app)
• ~/Library/Containers/com.microsoft.teams2.agent/ (a background helper)

Teams shows its login pages in an embedded Edge WebView, so there are cookies and local storage in here too:

• .../Data/Library/Application Support/Microsoft/MSTeams/EBWebView/
• .../Data/Library/Cookies/Cookies.binarycookies

Why it kept coming back

I deleted the keychain entry and cleared these folders, and Teams happily recreated all of it on the next launch. Two things were doing this.

The background agent. com.microsoft.teams2.agent keeps running after you quit Teams. If you delete the keychain entry while it’s alive, it just writes the tokens back from memory.

Keychain sync. The entry also lived in the iCloud keychain, not just in login.keychain. Deleting it locally wasn’t enough: macOS saw it was still in iCloud and quietly restored it.

What finally worked

1. Kill everything Teams. Quit Teams, then kill every process with “teams” in the name (case-insensitive), so the background agent is gone too.
2. Empty the containers. macOS won’t let you delete the container folders themselves, but you can clear what’s inside their Data/ folders, especially the cookies and the WebView storage.
3. Delete the entry from Keychain Access. Open the Keychain Access app, go to the iCloud keychain / All Items, find the OneAuth entries and delete them there. Doing it in the app made the deletion stick in iCloud too, and that was the step that finally made it go away.

Do them in that order. If the agent is still running, or the entry is still in iCloud, you’ll be right back where you started.