There are three documents the PSB needs and then they can cancel your residence permit without notifying you.

Your Employer must submit these three documents:
1．单位申请。（说明申请内容，用人单位盖章）；
2。原用人单位离职证明（说明离职原因及离开时间，由原用人单位加盖公章），如原单位已注销或关闭的，应提供有关部门的批文；
3。《外国人就业证》原件

1.Application Form from the Employer with an official stamp (stating what they are applying for, example: cancelling foreign teachers residence permit)
2.A letter proving you are not working for them with an official stamp (stating reasons why you no longer work for them, the date you left) if the company employing you shuts down they have to provide relevant documents.
3." Alien Employment Permit " Original OR Foreign Expert Certificate Original

If they dont have the Foreign Expert Certificate Original then they can report to SAFEA to cancel it; they say you cant be contacted and disappeared.