Delete books or audiobooks from your Mac in Books
When you delete a book, audiobook, or PDF from your library, it’s no longer stored on your Mac.
In the Books app
on your Mac, click Library in the toolbar.In your library, select the book or audiobook you want to delete, then press the Delete key.
If you’re using iCloud for Books and you delete a PDF, book, or audiobook that you imported, it’s deleted from iCloud and all of your devices where you use iCloud for Books.
Items you purchased from the Book Store or Audiobook Store are still in iCloud, even if you remove them from your Mac. They appear in your library with an iCloud status icon 
. You can download purchased books and audiobooks again.
You can’t delete items you purchased from the Book Store or Audiobook Store from iCloud, but you can hide them; click Sort By at the top right of your library, then select Hide iCloud Books. To hide books and audiobooks so they’re never in your library on any device, see Hide and unhide purchased books and audiobooks.