If you want to soft delete the record from Base Object you can use following code, please put corresponding values for items on which comment has been written:

        DeleteRequest request = new DeleteRequest();
        RecordKey recordKey = new RecordKey();
        recordKey.setRowid("345593");  // Rowid_Object of the Record in BO
        recordKey.setSystemName("SAP");  // Source System name of Record
        ArrayList recordKeys = new ArrayList();
        recordKeys.add(recordKey);
        request.setRecordKeys(recordKeys); 
        request.setDeleteBORecord(true);
        request.setSiperianObjectUid("BASE_OBJECT.MY_BASE_OBJECT"); //Name of Base Object 
        DeleteResponse response = (DeleteResponse) sipClient.process(request);

Above request will soft delete the record from Base Object i.e. it will set HUB_STATE_IND to -1 in the record. Soft deleted record can be restored using Restore API.