Cloud hosted environments - Clean up storage accounts in DynamicsDeployments-[AzureRegion] resource groups

If you are dealing with Cloud hosted Dynamics 365 for Finance / SCM environments, you might have noticed the mysterious DynamicsDeployments-[AzureRegion] (for example DynamicsDeployments-westeurope) resource groups in your Azure subscription. Over time the cost of these resource groups seems to become higher and higher. So far Microsoft has not shared any official information on how to clean up the contents of these resource groups, but such cleanup can save you a great deal of money.

What are these resource groups?
One resource group is created for each Azure region that you use to deploy Cloud hosted environments. And inside the resource group, there is one storage account for each LCS Azure connector that you have used when deploying environments.

What's in the storage accounts?

The storage accounts contain VHD images for all D365 versions that you have ever deployed. Whenever you deploy a new system, LCS checks if the storage account in the resource group for the Azure connector already has a VHD that can be used in the deployment. If not, it downloads the VHD and stores it in the storage account. 

The resource group can also contain disks of such Cloud hosted environments that don't use Managed disks.

You can use the Storage Explorer in Azure portal to browse the contents of the storage accounts.

What can be removed?

When you do cleanup you should be careful to not delete actual disks of your environments, which are in dynamicsdeployments folder. You only want to delete the VHDs that are used in the environment deployment, which are in product-ax folder. You can browse all the subfolders of product-AX folder and remove all VHD files that you find. Additionally there can be demo database backups (.bacpac) which can also be deleted.