Note, I’m referring to the very first post of that topic, as it is also described that certain Objects remain visible as “ghost Objects”, which seems to be a different issue with same effect (Object cannot be deleted).
Hey there, I’m pretty sure that files (including images, PDFs, etc) can’t be deleted at all right now – only Objects, Types and Templates are able to be deleted in the current versions.
I’d say to just ignore the file and delete it when deletion is available (very soon, according to recent updates). And as this is not a bug (although the failed image upload could be), I’ll close this issue for now. Feel free to flag if you disagree