Dear Soumarajeev,
I presume that you are an employee in the Dept. of Posts (and not in HR/Personnel of your dept.).
If so, you need not concern yourself about the format of the NOC as it is already with your Personnel Dept. You simply have to APPLY for it, and if everything is all right, such as:
No pending departmental action
No pending vigilance enquiries
No pending annual returns of immovable property, etc.
You will be granted the NOC by the dept.
@upendrataxconsultants, thanks for submitting a well-drafted NOC format for the required purpose.
Warm regards.