So you've finally succeeded running a windows virtual machine (VM) on your desktop. You play around the vm; copying files, installing & deleting applications and so on. After a while, you found out that your vm is using let say 20gb out of 100gb (which you set during creating the vm) disk but your local machine (host) report that you have used up 50gb. So how can you claim back that extra 30gb in your host ?