Elimination of books of sorts

Peace and blessings
As part of the Passover cleaning and the elimination of chametz, a question arose for one person about a slightly broader cleaning – the elimination of the books of the Book of Zechariah, but unfortunately the books were not his. He asked a rabbi whether it was permissible to steal the book from him, and he did not know about it. His answer was, "Ask Rachel, our mother."
I understand from him that it is permissible. I remember you once wrote about a similar case, where you lent a book to a yeshiva student, and the supervisor lost the book for good, and the end of the story was that he paid you for it.
I would love to know what the halachic reasons are for charging a fee on this issue.