Finding things in Finder · Storage Studio in Finder's sidebar
Why is there no eject button next to Storage Studio in Finder, and do I need to install anything for it?
Short answer: It's a built-in Finder location like iCloud Drive, not a mounted disk, so there's nothing to eject and nothing extra to install. Turn it off in Cloud Accounts → Mounting, or quit the app to remove it.
Because it isn't a mounted disk — it's a built-in Finder location, like iCloud Drive or Dropbox, which don't have eject buttons either. Nothing extra needs installing; it comes with Storage Studio.
To make it go away, either turn it off in Cloud Accounts → Mounting, or quit Storage Studio, which removes it until you open the app again.
The only exception is the fallback drive Storage Studio uses if the location can't start — see the fallback drive.