When a Content Library is deleted, what happens to the files contained on the backing storage?

Files are not left unchanged; the deletion operation explicitly removes all content from the backing datastore along with the library object itself.

When a Content Library is deleted in vSphere, the platform actively removes all library item files and metadata from the associated backing storage (datastore). This is a destructive, permanent operation - vSphere does not leave files in place or mark them as orphaned; the storage is reclaimed immediately.

vSphere does not have a mechanism to mark Content Library files as orphaned upon deletion; the files are removed rather than flagged for later cleanup.

The containing datastore folder is not marked as orphaned; the folder and its contents are deleted as part of the Content Library removal process.