Hello @Nguyen Minh Hieu ,to unlock your Microsoft Account from an Entra ID tenant, you will need to reach a Global Admin for the aforementioned tenant. To ensure you're logging into the right tenant, use the following URL format: https://entra.microsoft.com/{tenant-id-or-name}
. Eg: https://entra.microsoft.com/mytenant.com
If the issue persists, please contact us trough one of the For Business users Global Customer Service phone numbers.
Let us know if you need additional assistance. If the answer was helpful, please accept it and rate it so that others facing a similar issue can easily find a solution.