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.
This makes me think that you want to put the book into calibre only long enough to convert it to the desired format. After that, you want to manually manage your library without using calibre. Is that right?