The solution is to hide them.
Instructions in this article apply to macOS Catalina (10.15) and iOS 14.
Whatever the reason, here’s how you delete books from your Books library on a Mac.
Open theBooksapp on your Mac from the Applications folder or the Dock.
Select theLibrarytab at the top of the Books app andAll Booksin the left panel.
opt for book you want to delete to highlight it and then press theDeletekey on your keyboard.
In the confirmation screen, selectDeleteto remove the book from the Mac.
If you have Family Sharing set up, your family members can’t see or download any hidden items.
In theBooksapp on the Mac, select theBookStoretab at the top of the screen.
SelectFeaturedin the sidebar on the left side of the screen.
key in your Apple ID/Apple Account and password to continue.
Locate the book you want to hide and press theXin the corner.
Confirm that you want to hide the book by pressingHidein the confirmation screen.
put in your Apple Account information to continue.
In some versions of macOS, this option is called “Apple ID.”
Scroll down to the Downloads and Purchases section and selectManagenext toHidden Purchases.
Open theBooksapp on your iPhone or another iOS machine.
TapLibraryat the bottom of the screen.
Locate the book you want to delete and tap thethree dotsunderneath it.
(If it’s in a collection, launch the collection first.)
SelectRemoveon the screen that opens.
If you prefer to hide the book on the iOS equipment rather than remove it, tapHide Bookinstead.
Open theBooksapp on your iPhone or other iOS equipment.
TapReading Nowin the bottom left corner.
Scroll to the top and tap theaccounticon.
TapManage Hidden Purchases.put in your Apple Account to continue.
TapUnhidenext to any book to send it back to your library.
TapDoneto exit the screen.
