What is the ruling on disposing of CDs containing Islamic materials by breaking and discarding them for security and compelling reasons, and how does one repent from that?

It is permissible to destroy damaged Quranic audio tapes that cannot be used, and there is no sin in discarding them in the trash, because they do not carry the sanctity of the Quran written in its letters; rather, they are merely an audio recording that can be erased. It is also permissible to destroy them if harm is feared from them and it cannot be averted except by doing so.