Also , if there is no hope then can someone help me with the de-registration process in Zurich . I will have to leave Switzerland in this case very soon.

Your employer could appeal, but L to B conversions probably dont happen if the contract is for a few more months. I dont know if any L permit extension after the typical two year limit for L permits is possible. Ask your co. if any such application is possible.

For deregistering, go to the same gemeinde office where you registered/applied for permit renewals and fill in the needed form. Make sure you get an attestation which you will need to show at emigration in case you need to surrender the permit while deregistering.

Does anyone know if we appeal against the decision can help !!

Also , if I want to reapply for the fresh L permit after leaving Switzerland , then what is the colling off period ?....I am a non-EU