Dear Devi Chand,
My opininon on your query is as under
1) See whether the product which is removing in your brand name after sterlising is covered under third schedule to Cenral Excise Tarrif Act 1985? if yes then you need to pay the central excise duty on the MRP (less abatement ) of the said product under section 4A of the act because process of labeling and relabeling amounts to manufacturing if product is covered under third schedule to CETA
2) If it is not covered under third schedule to CETA then varify whether process of sterlising is manufacturing? i.e. whether because of sterlising there is change in product name, form etc ? wheteher there is no customer withou sterlising ? if answer of yes to above then duty is payable on the selling price as charge by you.
3) if process does not amounts to manufacture, simply reverse the credit as you have taken earlier. and show the remark on invoice as Input removed as such under 3(5)(a)
4) also intimate to your range suerintendent regarding above so that there is no mis-representation of facts