Moderator Notice
@EvM1 - posting the same thing 3 times won't get you an answer any sooner - in fact to the contrary it will irritate some responders. I appreciate you're probably stressed but...
We've (Me & Dr. Drib) closed the other two threads
When you Remove a library from calibre it does not remove the library folder or it's contents, as you've discovered it merely removes the linkage within calibre to that library folder.
To copy or move books between libraries use the Copy to Library option in the Book List context (right click) menu. You can add Copy to Library to your toolbar via
Preferences>Toolbars if you don't like using context menus.
The Save to Disk feature is there to allow users to save books in different folder hierarchies with different file names. And whilst it could be used as the means to backup a library, restoring from it wouldn't be as easy as keeping a backup with a 3rd party purpose designed backup tool. What operating system are you using - Linux, OSX or Windows?
BR