1. Just don't care and leave. If you want to leave China, you will be OK as long as you haven't overstayed, you will not be asked to show your FEC by immigration at the airport when leaving China.

2. Contact the local issuing authority yourself and tell them you are no longer working at the school or for that agent. If your employer hasn't handed the FEC over to you and kept it instead, it is illegal but should not prevent you from telling them.