Answer
(Fatwa: 179/179=M)
If the purpose of deleting audio files and word of the Holy Quran is replacing them with songs, pictures or saving wrong matters then it is impressible. And if the deletion is meant to protect the Quran from desecration then it is not only permissible but commendable, as a rule of Fiqh says:الا مور بمقاصدها
After all, in both the ways, it will not be called destroying the Holy Quran.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband