Reclaiming disk space from AppVM's

Hi,
I deleted around 14 gigs from my AppVM qube but “Total disk usage” software from system tray shows me that it has only 1 gb less.
Maybe someone has an idea how to reclaim that space because now I see no reason in deleting anything if I cannot free disk space I delete.

Thank you. Can I see somehow which AppVMs are still keeping my “revisions” now?

All of your VMs are keeping 1 revision by default.