List orphaned disks in Azure using AZ CLI or Powershell
If you have a ton of compute and storage resources in your Azure environment, it can be difficult to tell which managed disks are orphaned or not mounted to a virtual machine. This Microsoft Doc [A] has the AZ CLI command, but it's buried in a larger task to delete the found objects. This Docs page also doesn't have the Powershell equivalent and I prefer to use Powershell.
To find these disks, run one of these commands in a Cloud Shell or other Azure connected terminal:
AZ CLI:
az disk list --query '[?managedBy==`null`].[id]' -o tsv
Powershell:
Get-AzDisk | Where-Object {$_.ManagedBy -eq $null}