Gravity Forms must create an entry in order to function properly. Rather than truly disabling entry creation, the Disable Entry Creation perk will automatically delete the entry and any associated files after the submission process has been completed. Additionally, if the form has a User Registration feed, the entry will be deleted once the user has been activated, created or updated (depending on how your User Registration feed is configured).
To disable entry creation for any form, just activate this perk and head to the form settings for whichever form you’re working with. Scroll down to the “Form Options” section near the bottom and check the “Disable entry creation” checkbox.