The attachment feature is great… but it’s lacking the ability to remove an attachment when you u/l the wrong one or need to update the attachment (for example, updating K’Rect. (You can delete the link, but not the file, and can use the edit history to find removed links. I don’t know if you can do it with others’, but if the OP can, the staff probably can.)
The system is set to remove any files that aren’t linked to by any posts after roughly 48 hours. Try deleting all references to the file and waiting through that grace period and see if it’s still there.
Checked, and it’s working.
Good to know.