Hi,
I will use three different approaches to your issue:
First one you can create a Target group using your marketing attribute and a filter based on the value you want to delete.
Once you have the Target group you can use the Marketing Advanced Tools transaction(
CRM_MKT_TOOLS) and update the values from ST03 to empty (If it is allowed on your marketing attribute definition)
Second you can first use on your code a call to FM CRM_MKTBP_READ_CHAR in order to obtains the BPS the value of the attributes in case is the one you want deleted execute
CRM_MKTBP_CHANGE_BP updating the new value.
The third option will be to make an selection of CABN and AUSP and UPDATE directly the registers on the table.
I hope it helps,
Regards,
Pedro