Remove old accounts from Teams Mac sign-in screen; cache reset did not help

Do not delete opaque OneAuth Keychain records individually; remove the old identity only if Keychain Access or the Microsoft single sign-on interface exposes it as a named account.

1. Try the supported Keychain removal

Microsoft’s documented macOS procedure is:

1. Quit Teams completely.
2. Open Finder → Applications → Utilities → Keychain Access.
3. Select the login keychain and All Items.
4. Search for the old email address, account name, or old organization domain.
5. If a result clearly identifies that account, right-click it and select Delete “[account name]”.
6. Reopen Teams and inspect Pick an account. ^1^

Do not delete entries identified only by an unfamiliar GUID or internal OneAuth ID. Microsoft identity libraries can share a Keychain across applications, so deleting shared credentials can remove tokens used by Outlook, OneDrive, and other Microsoft apps—the exact collateral reset you want to avoid. ^2^

Signing out of Teams does not remove a device-level identity: it removes Teams’ app data, while other applications and macOS single sign-on can continue exposing the account. ^3^

2. If this Mac uses Microsoft Platform SSO

Check whether Microsoft single sign on for macOS is installed and has an Advanced menu. This applies primarily to organization-managed Macs using Microsoft’s SSO configuration.

1. Open Microsoft single sign on for macOS.
2. From the macOS menu bar, select Advanced.
3. Look for Remove account from this device.
4. Use it only if the interface identifies the obsolete work or school account.

That operation removes the work or school account and its SSO authentication tokens from the device. Do not choose Deregister unless the intention is to remove device registration and disable SSO entirely. ^4^

If the Mac is managed and the control is unavailable or the old identity is provisioned by Platform SSO, the organization’s administrator must remove or adjust the applicable account/SSO configuration. Platform SSO requires MDM enrollment and is delivered through device policy. ^5^

When neither interface identifies the account

There is no documented, reliable mapping from the opaque OneAuth IDs in Keychain Access to the email addresses displayed by Teams. Because the Teams cache reset has already failed, repeating it or reinstalling Teams is unlikely to provide selective removal.

At that point, the safe choices are:

• Leave the stale picker entry in place; it does not mean the account remains signed in.
• Ask the current or former organization’s administrator whether the Mac has an SSO or Platform SSO registration for that identity.
• Open a Microsoft support case for account-specific cleanup.
• Use a full Microsoft identity reset only as a last resort, accepting that all Microsoft apps will require authentication again.

References

1. Sign out or remove an account from Microsoft Teams
2. Configure SSO on macOS and iOS
3. Sign out of Microsoft Teams
4. Manage preferences Entra Id for macOS
5. Configuring macOS Platform SSO (PSSO) to meet NIST SP 800-63 and EO 14028 Requirements