Hello @JZ,
Thank you for connecting over the call.
As we discussed, your initial concern is that users are being created with the onmicrosoft.com domain instead of your custom domain, and you are also looking to delete two users from your All users list. During the call, we verified that the custom domain you want to use as the suffix for user principal names (UPNs) has already been verified in one of your Entra directories—let’s refer to it as Tenant A.
For more details about verifying custom domains in Microsoft Entra ID directories, please refer to the following documentation: Add a custom domain to Microsoft Entra ID.
Given this limitation, you would prefer to continue using the custom domain within the same directory without making any changes to its setup.
Since the domain is already in use in Tenant A, you are planning to migrate the database from Tenant B to Tenant A so that all management can be centralized in a single tenant, avoiding the need to maintain multiple tenants.
Regarding the database migration from Tenant B to Tenant A, please find the options below--thanks to Oury Ba-MSFT for sharing this helpful information:
Migrating a Flexible Server from Tenant A to Tenant B with minimal downtime should be possible through two options:
- Azure DMS enables online (minimal downtime) migrations between tenants by streaming data continuously from source to target. This is our primary recommendation for most tenant-to-tenant scenarios. Tutorial: Migrate from MySQL to Azure Database for MySQL - Flexible Server online using DMS via the Azure portal - Azure Database Migration Service | Microsoft Learn
- As an alternative, you can set up Data-in Replication to replicate data from the source server in Tenant A to a new Flexible Server in Tenant B. This also allows for a low-downtime cutover when you’re ready. Configure Data-In Replication - Azure Database for MySQL - Flexible Server | Microsoft Learn
I hope this information is helpful. Please feel free to reach out if you have any further questions.