1. Sir, Kindly see the provisions of Section 93A of ESI Act, 1948.
2. There is no system of cancellation of any code number, but you can request for closure of the Code Number from the date of such merger. You can send a request to the appropriate Regional/Sub/Divisional Office of the ESIC to which your establishment is covered intimating all the facts of the merger of one unit with another unit and assure them that the compliance in respect of employees of the establishment merged will continue to be done on the ESIC code number of the firm to which the said establishment is merged. Therefore, you may request for closure of particular code number.
3. Please enclose the documents relating to such merger orders viz. resolution of the company, change of partnership deed, order of registrar of companies etc.etc.
4. Please also send the copies of said letter to appropriate Branch Manager of ESIC and Social Security Officer to which your firms are attached for further necessary action and information at their level also.