Unable to delete BizTalk Services Artefacts from the portal
To resolve the issue, go to https://resources.azure.com/ Go to particular subscription => resource group. Find the artefact and do the delete operation.
To delete Access Control Namespaces
Log in to the old portal
https://manage.windowsazure.com/
From the left navigation pane, select Active Directory
On next page, go to Access Control Namespaces
You should find your ACS namespaces over here and be able to delete those.