Delete books from your Mac in Books
When you delete a book 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 you want to delete, then press the Delete key.
If you’re using iCloud for Books and you delete a PDF or book that you imported, it’s deleted from iCloud and all of your devices where you use iCloud for Books.
Books you purchased from the Book 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 again.
You can’t delete books you purchased from the Book 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 so they’re never in your library on any device, see Hide purchased books.