B2C directory cannot be deleted with Visual Studio Enterprise subscription
Following all the instructions available, it is not possible to delete a B2C tenant that was briefly used for development purposes.
There is only one user in the tenant.
There are no applications remaining in the directory. (other than Office 365 Management APIs which cannot be deleted)
The classic portal still reports that there are applications remaining and will not delete the B2C directory.
Feedback has also been submitted from portal.azure.com with a screen shot displaying that it thinks there are App registrations while listing no app registrations.