Changing Z work visa into X student type

Hello!
My name is J and I currently work in Changchun as a foreign teacher. I want to go to Jilin university for the spring semester next year (January-July) but I don't know how tricky it will be for me to change over from a Z into a student type. Does anyone have any advice or helpful tips for me? I know that I will need to be amicable with my employer in order to get a release letter but other than this i'm not sure what else I need to do to prepare.

Thanks for your suggestions!