Dear Rajiv Singh
There is no need to get the Work completion Certificate from Regional Labour Commissioner. You must obtain the Completion Certificate from the Principle employer in Form VI-A and you have to prepare Completion Certificate in Form VI-B. Then submit the same to Labour Commissioner to get the Labour Licence cancelled and get the Labour Security Deposit back, for which you must submit the Original Labour Licence, Xerox copy of Security Deposit Challan.
You will get the Security deposit back. If you are starting some other work in the same area, the amount can be adjusted for the new project also.