Are you looking for this??...
Action-> Download -> When you click on CSV icon it will send a request as "CSV".
Edit the columns which you don't want to include in csv output file.
Go to Condition section,
Condition Type: Request Is NOT Contained within Expression 1
That column will not include in the csv file.
Please try this, hope it will work....
You can hide it by putting a condition on the column of type PL/SQL Expression and using the following as the expression:
To stop a column from showing up for an email, you can use the following:
NVL(wwv_flow.g_widget_action, 'EMPTY') != 'SEND_EMAIL'