Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
I assume the issue happens when you try to delete the user form the portal? If so, make sure to use the Feedback button to report it.
Did you try to remove it via PowerShell? You can use the Remove-MsolUser cmdlet for that.
Also, is the user synced from on-prem? You cannot use the portal to delete synced users, you have to use PowerShell.