Hello @Kim Zachariassen ,
Thank you for reaching out to Microsoft Q&A platform. Happy to answer your question.
You need to make sure that the resource provider "Microsoft.AzureStack/registrations" is registered under the subscription. Appears this provider got unregistered. Hence it fails to delete the resource of its type.
Possible Causes:
You receive these errors for one of these reasons:
- The required resource provider hasn't been registered for your subscription.
- API version not supported for the resource type.
- Location not supported for the resource type.
- For VM auto-shutdown, the Microsoft.DevTestLab resource provider must be registered.
Example:
Detailed steps to register a provider is available here : error-register-resource-provider
Please "Accept as Answer" and Upvote if any of above helped so that, it can help others in community looking for remediation for the similar issues.