How to delete an operation from order using the bapi

Can somebody please tell me how to delete an operation from order using the bapi

BAPI_ALM_ORDER_MAINTAIN.

Following was the test data for the BAPI.

000000 OPERATION DELETE 0000040052810070

000000 SAVE 0000040052810070

Even I tried entering the operation table. The BAPI control ends fine, but when I check the order using IW32, the operation still exists.

So, can you please tell me where Iam going wrong.