Is "Aud" the name of the column that you want to delete? If so, use the Delete Column action from the Utility - Collection Manipulation VBO. Pass it the original collection and "Aud" as inputs, and the updated collection will be the output.
If the first column name is unknown, use the Get Collection Fields action from the Utility - Collection Manipulation VBO. This outputs a collection containing all the field names. The first row of this collection contains the name that you should pass to the Delete Column action as stated above.