Is it permissible to burn a torn and unused Mushaf due to damage to its pages and its exposure to dust and rainwater?

A Mushaf (copy of the Qur'an) that is suitable for reading should not be burned due to its sanctity. Burning it out of disdain constitutes disbelief. However, for a Mushaf that is not suitable for reading, such as one that is torn or damaged, there is no harm in burning it to preserve its sanctity, and this might even be obligatory.