I didn't cancel my visa before I left China, but I need to re-enter for tourist purposes. What to do

I was given a 2 year X type, but I left 1 year before my X type expired (July 2016). But I did not cancel it thinking I will not need to return again. I need to re-enter China not on a student X type anymore but on tourist L type. What should I do? How do I go about cancelling my current student X type and applying for a tourist one?