To take a snapshot of the current state of the virtual machine, go to your personal account, select the machine in the Cloud tab. You will go to the interface with detailed information about it, as well as available actions. Click the "snapshot" button.
Write a snapshot's name and Take a snapshot.
Note that You can only have 3 snapshots at a time. Each snapshot exists for 24 hours and is then deleted. Enter a name for the snapshot and click on take snapshot. Wait a bit - and your snapshot will be displayed in the list of available ones. Use it to be able to restore the desired state.