Hi,
The following blog post goes through the deletion of an Azure VM and cleanup steps with PowerShell:
How to Remove an Azure Virtual Machine and Cleanup with PowerShell
The following script can also find and delete unattached Azure disks:
Find and delete unattached Azure managed and unmanaged disks
The Azure VM deletion is also a process that is being improved, see the uservoice here:
https://feedback.azure.com/forums/216843-virtual-machines/suggestions/8945692-delete-vm-with-all-associated-resources
(Please don't forget to mark helpful replies as answer)
Best regards,
Leon