Originally Posted by crossi
There is a icon within the calibre program for deleting or adding a formats in the edit metadata function . I wouldn't try it manually by just opening the folders. Is there a problem with that function within calibre? I've used it for changing text or epub into mobi files and it seems to work ok.
I will get an external harddrive though for backups. I didn't know about the shorter life of the usb drives.
That is (one of the many locations for deleting ) the 'proper' way to delete a book from Calibre. As long as Calibre presents the option, the database stays properly in sync with its contents.