I am unable to delete the 'default' subnet from a VNet that I am no longer using. The error is: "Subnet default is in use by /subscriptions/{guid}/resourceGroups/mpi-prod-westeurope-rg/providers/Microsoft.Web/serverfarms/mpi-web-asp and cannot be deleted."
The problem is mpi-web-asp is an App Service plan that was deleted about a week ago. I attempted to create a new App Service Plan with the same name however, as expected, that did not work.