All operations in the production not getting deleted

Dear Experts,

Please advice.

My case is we have collective orders.

User has set deletion flag for child order .

In the production order for which deletion flag was set there are 4 operations, After deletion flag was set to production order first 3 opeartion are flagged as deleted with status "dlt_rel" but one operation is left out.

Please advice how to delete all operations in the production order at a time.

Regards,

Krishna mohan