I ran a utility (WinDirStat) to identify visually what it on my 150 GB SSD boot drive, and was surprised to discover that fully 23%, or 34 GB, are taken by SONAR Platinum's Command Center.  The path is C:/Program Data/Cakewalk/Command Center/Downloads
 
Many of these files are dated from 2015.  Many are clearly older along with newer versions.  I assume I can delete a lot of the older ones, especially after sorting them by name and identifying the older versions of each.  But is there any reason NOT to do this?  Do any of these files have to be kept at all, after being installed by Command Center?
 
As you can guess by its size, I've had this SSD boot drive for awhile.  It's relatively small, and thanks to Command Center, getting rapidly filled.
 
Thanks.

The files you download from Command Center are just installer files, so deleting them won't impact Sonar functioning at all . . . as far as reasons to keep them, maybe keep the most recent downloads in case for some reason you have to do a rollback, or if you have a really slow connection it may take a while to re-download all the files, if you had to re-install everything.
 
You can also tell Command Center to download them to another larger drive if you have that available on your system. I usually download them to my OS SSD drive and then move them to storage . . . I've only needed them once to do a rollback last year some time.

I use the same technique as noynekker

Ditto.
 
I keep the last 2 only.

So, to alter the location of where Command Center DOES download files, launch Command Center, then click on the Gear button, which opens settings.  Click on the Paths, and change the path for downloads to some other drive that has more available room.
 
I don't recall whether or not changing the path will result in Command Center offering to copy things over to the new location or not.  If it doesn't, you can simply do a cut/paste of all the existing downloaded installer files from the old location to the new, and then moving forward - any new downloads would be located at the new path location.
 
The other comment made in another post above about manually trimming the downloaded installers is also a good one - where YOU decide how far back you want to be able to go with doing any rollbacks, and then manually delete any installers that are beyond how far back you are likely to want/need to rollback to.  Even if you were to want to rollback to a version you had deleted the installer for, Command Center would simply download that version again.
 
I have a primary drive (C:) that is solid-state, and only 110 GB, and by moving Command Center downloaded content to another drive, and by using the Location tab for all of my user's basic folders (Documents, Pictures, Downloads, Videos, etc.), I moved all of my user data off to a different drive too - and I now have over 50 GB of free space remaining on that rather small C: drive.
 
Hope that helps, 
 
Bob Bone
 

All answers were most helpful.  Thank you!
 
Off to delete most of the files now...