To see what data would be deleted if you would uninstall some specific app, simply select the app (e.g. Deluge) and click Uninstall and the next screen shows every path that Uninstalr sees to be relating to this app and which it would remove should you proceed.
Do notice that you are recommended to review this list of paths before ever uninstalling anything and if you see any paths there that you do not wish to be removed, you can simply edit the list and remove such paths.
If there are any paths you think should not be there, please report them here and I will see if I can find the bug and fix that.
The path visible on your screenshot is clearly relating to Deluge and that is why Uninstalr detects it and suggests it to be removed. But as said, this is only a suggestion from Uninstalr and you can edit the list of paths before actually removing anything.