Hi @Stephen Aspey,
Thank you for reaching out to us with your query regarding deleting AI Service endpoints after resource deletion.
It's possible that the endpoint URL may still be active due to caching or DNS propagation. It may take some time for the endpoint to be fully removed. I suggest that you try to access the endpoint after a few hours or a day to see if it is still active.
You can also review the Azure documentation on deleting resources in Azure for more information.
If you're still unable to resolve the issue, you can try creating a new AI Service with a different name and endpoint URL.
I hope you understand! Thank you.