How can I prevent Gravity Forms from saving entries?
This is a question that comes up every so often. The answer is, you can't. Gravity Forms needs to save the entry for those values to be available for use in notifications, confirmations and to send them to third-party services.
What you can do however is delete the entry at the end of the submission process. The following code snippet will add a checkbox to the Form Settings page, check the box and the entry will automatically be deleted.
This snippet requires the latest version of Gravity Forms be installed, Gravity Forms 1.8.6 was released earlier today so go and update. You can then add the following code snippet to your theme functions.php file or custom functionality plugin, you don't need the <?php from line 1.