You should never throw books away. You can always give them away in a heartbeat, and people all over the world need them. If nothing else, donate tehm to the nearest Goodwill or Salvation Army where they will help employ, feed, cloth, educate, entertain the poor and the homeless.
There are also poor countries all around the world who would give anything for your used books, regardless of the language difference. If you could see the way people from age three to eighty-three act in many parts of Africa act when they see a load of books coming in, you'd never again throw away a book.
When I "throw away" books, they get tossed only because I don't want credit for giving them to those who will take them to people who want books more than shoes. But you can, if you wish, take a tax credit from almost anyplace, including Goodwill and The Salvation Army.