You have two options - set your iPod to "Manually Manage Songs and Playlists" and just delete it from your iPod. You will lose the Auto-Sync function of iTunes but you will have complete control over what is or isn't on your iPod (it treats the iPod and your Mac as two separate libraries that you can transfer music between, you won't lose any music)
Or, you can set your iPod to update only checked songs, uncheck the book in iTunes then control-click on the iPod in the source list and hit "Update" - it should delete the book from the iPod but not iTunes.