Letter To The Principle Employer To Get Work Completion Certificate?

Myself working in reputed company.now we have finished our work. We have to give application to labour office for withdrawal of labour license which we have received from labour commissioner.
We need your help for writing a letter to the principle employer to get work completion certificate.

against form 5 of PE, you have obtained the licence, in which the work period is mentioned, now the contractor is expressing that work is finish, not the principal, who has issued form 5
just ask the principal to issue a completion against form 5 and treat the same is cancelled, that would be enough for contractor to surrender his licence.
However, as the licence fees is paid for a year, contractor may keep his licence valid, and a valid licence renewal is also easy, in comparison to get a fresh licence.