Cannot delete Microsoft Entra tenant – 401 – User has no directory roles

I accidentally created a Microsoft Entra ID Free tenant for my domain franzschmidt.de.

The tenant contains one user only, no groups, no applications and no devices.

My custom domain is verified.

However, my user has no directory roles assigned, therefore I receive 401 – You do not have access to this data whenever I try to delete the tenant.

The Microsoft 365 Admin Center asks me to "Get administrator access", although I am the only user in the tenant.

We do not use Microsoft 365 Business, Exchange, Teams or Azure. We only use Microsoft 365 Family with a personal Microsoft account.

How can I restore the Global Administrator role or request Microsoft to delete this orphaned tenant?