virtualbox.org

I have deleted from VirtualBox console some unused VMs, but it says that it can't safely remove them and, even if it doesn't show them in Virtual Box console, my old VMs are still in my hard disk. Can I delete these folders manually in order to save space on my hard disk?
Thanks!

Provided they do not contain hard disks cross referenced by other VMs (you would have had to do this manually, so you must know) then you should be able to safely delete them. However, perhaps you should back them up first.

I don't have hard disks cross referenced by other VMs, thanks for your answer!