@Domenico Rossi Thanks for posting your query on Microsoft Q&A.
The error message indicates that the storage account has some active image(s) and/or disk(s), which prevents deletion.
Resolution steps:
#1To remove classic Disks, follow these steps on the Azure portal:
-Navigate to the Azure portal.
-Navigate to the Disks(classic).
-Click the Disks tab.
-Select your data disk, then click Delete Disk.
-Retry the Delete operation that previously failed.
#2. The disk lease associated with the page blob (.vhd) also prevents deletion.
Go to the Azure portal, navigate to OS images (classic), and delete the image associated with the storage account.
This action will break the disk lease, allowing you to delete the page blob itself.
A storage account or container can't be deleted if it has a single Disk.
Additional reads:
Try the suggestions above and please let me know in the "comments" and I would be happy to help you. Comment is the fastest way of notifying the experts.
If the answer has been helpful, we appreciate hearing from you and would love to help others who may have the same question. Accepting answers helps increase the visibility of this question for other members of the Microsoft Q&A community.
Thank you for helping to improve Microsoft Q&A!