virtualbox.org

The main VB windows shows there are no snapshots for my VM, but there are some old files living under (VM directory)/snapshots:

01-Oct-2013  05:58 PM       347,622,122 2013-10-01T22-58-50-091246100Z.sav
06-Jan-2014  10:47 AM       854,006,470 2014-01-06T15-46-25-550908100Z.sav
16-Feb-2016  03:32 PM       962,404,261 2016-02-16T20-31-52-671555400Z.sav
01-Oct-2013  05:58 PM           131,072 {3a8f19da-f68a-4eb9-b304-938a93e392c7}.vmdk
01-Oct-2013  05:58 PM         6,094,848 {74ecb172-f795-4464-b4f8-f3b0dc2fa190}.vmdk
01-Oct-2013  05:58 PM        18,939,904 {fdc8110f-9427-4ca9-a2fa-f3a1179ee67c}.vmdk

I need to make room on this drive. Apart from the .sav file from last night, is it safe to delete the other five?

It is impossible for us to say. There are many reasons why files are created in the Snapshots subfolder. For example, when you create linked clones - and that will not show up in the Snapshots tab.

1) Is it possible to address the .sav and .vmdk files separately? Specifically, I could live with 25MB of .vmdk files if I could delete the two oldest .sav files.

2) Also, is it possible for me to make a normal clone of my VM on another disk, allowing me to delete the existing VM? (If there were other VMs using its files, I would get a warning — and I have no interest in other VMs; the existing one is the one I use every day) After deletion, I could relocate the cloned VM from the other disk back to y main disk. How does that soiund?

SAV files are saved states. If you snapshotted (or possibly link cloned) a VM that was in a saved state then these would still be needed.

The short answer to your question is: no, you cannot use the host OS to delete any VirtualBox file, at any time, unless the VM concerned no longer exists (and sometimes not even then). Always use the GUI manager.

Also the main lesson: linked clones and snapshots are a poor choice for someone who is concerned about disk space!