Compress VirtualBox virtual disk image (VDI) to maximum

VirtualBox actually save your deleted data in vdi file.
If later you compress this vdi image then it is good to run hdd wipe

You can run ccleaner inside the VirtualBox OS:

When you run this command the VDI file actually does not shrink, but
if you now compress VDI file - it will be much smaller.

Home:
https://www.ccleaner.com/ccleaner