C-c m d prompts for a FDirectory, when it actually seems to ask for a URL. Whatever is entered then becomes the default directory for further operations. I find this rather counter intuitive. Rather, I would expect to be asked for the document's URI. I would also propose that there is confirmation (y/n) for the deletion of the document. If the current buffer points to a document in ML, its URL should be used to prepopulate the URI prompt.