Moving folders · How moving folders works
How do I delete a file I've already moved to the fast drive?
Short answer: Move it back first and delete it normally, or delete both the copy on the drive and the link on your Mac. Deleting only the link in Finder leaves the data on the drive; the Relocated panel then offers a Delete chip to clean up the leftovers.
The cleanest way is to move it back first and then delete it as usual — or, if you no longer need a whole moved folder, delete both the copy on the drive and the link on your Mac. Deleting only the link in Finder removes the pointer, not the data: the file still sits on the fast drive taking up space.
If that happens, What's Using Space's Relocated panel flags the folder (data on the drive with no link at the original place) and offers a Delete chip that cleans up the leftover data and Storage Studio's record together. Deleting only the data on the drive leaves a link pointing at nothing — the same clean-up handles that case too.