Hi, where can I change my work visa to a tourist visa in China. I am now in Suzhou.

I have working visa, which expires july 31. I have already finished my work contract and now traveling, can I change working visa for tourist one. And also working visa was given to me in Guilin, but now I am in Suzhou, so should I come back to Guilin or I can apply in Suzhou PSB? Thank you.