Function module/BAPI to delete assignments as VL02n

In my program I have a requirement to delete assignment which is done through VL02n

Following are the steps followed:

1. Enter the outbound delivery no. in VL02n

2. Click on Pack button

3. In Pack Material tab, select all Handling Units and click Delete assignment button.

I want this functionality to be written in my program. I debugged and found the FM V51P_DELETE_RELATIONSHIP.

Following is my code:

   CALL FUNCTION 'V51P_DELETE_RELATIONSHIP'
    EXPORTING
      if_control  = 'X'
      it_hus      = lt_venum      "table which contains all the Internal HU number associated with the delivery
    IMPORTING
      et_new_hus  = lt_hus
      et_messages = lt_messages
    EXCEPTIONS
      fatal_error = 1
      OTHERS      = 2.

But this doesn't help. Is there any other steps that are supposed to be followed after this or should I use a different FM?

Please give inputs on this...