Many people in Pakistan believe that praying mat should be folded at the top left or right corner, making a triangle, when not praying. Is this a Hadith or a ayath form Holy quran? Please help me.

Isn't there a senior in your prayer group who can tell you this. It is obviously tradition to fold this way. Why would you question tradition ? Is it too much work for you to fold it the way everyone else does ? Please tell us.