A common problem in azure is identifying resources that are no longer used, underutilized or not quite working. Azure Advisor tool is the best option to fine tune your Azure bill.
To find the best recommendations go to:
From Home –> Cost Management + Billing –> Cost Management, scroll down on the options and select View Recommendations:
From here you will see the recommendations for your subscription, if you have orphaned disks, they will be listed.
We can review the SQL Data base recommendation, as you can see there is a recommendation to downsize with a recommended SKU based on utilization, you can download the information and create alerts.
For more documentation on Azure Advisor