Reverting changes to your virtual machine

Today you'll finally have the opportunity to get even with your boss! The Snapshots feature in VirtualBox will let you scare the living daylights out of him! How, you may ask? Well, you can take a snapshot of your working virtual machine, then delete some important parts of your guest operating system and, when your boss realizes that he has lost all the work he's done for the last few days on his virtual machine, you'll come to the rescue by reverting the change to his virtual machine and restoring his sanity! And now let's see how to do that...