Often Forms are created to send a copy to the user upon submission due to Form Action being set up to email the form to the User, this can be edited though form actions on each form template as needed.
In the Web Portal go to Forms > Existing Templates > select the Edit Arrow for the Form you would like to alter the Form Action > Actions > Send Email Action (or one of the types of email sending actions that may be set up).
Scroll to the bottom of the page and look for a Send To box that has the 'User Email' action and select Remove > Save Action.
