Change working permit (Guangzhou)

Hello,

I need to change employer working permit and renew my resident permit, I worked in Beijing, now I found a job in Guangzhou, my working permit has not been cancelled, and my rensident permit will expire the 24 june Protected content . Actually, can i tranfer my working permit to the company in guangzhou providing a release letter from the old company and others documents or should i to restart all procedure again with invitation letter, medical certificate, employment license, diploma ecc.. ? Thanks

regards