Originally Posted by highstream
With regards to what shows in the Library view (UI), what I'm trying to work around is having endless list showing in the UI. I don't really need to delete any formats, just what shows (though the epub delete I tried didn't delete the file from Windows). The way I see it, as long as the right format file is in Windows, Add books allows me to bring anything back into the Library UI that I need to work with, such as for collections in Kindle.
Make a Filter:
All that will show when the filter is in effect is entries WITH actual books (any format) inside Calibre
And Remove Books Deletes Only books INSIDE Calibres Library (and that works if the file system user rights have not been messed with)