Disable New User Notifications

/* Remove new user email for admin and user on Registration form */

remove_action( 'edd_insert_user', 'edd_new_user_notification', 10, 2 ); 

/* Remove new user email for admin and user on Checkout Registration form */

add_action( 'edd_pre_process_purchase', 'prefix_remove_user_emails' );

function prefix_remove_user_emails() {

    remove_action( 'edd_insert_user', 'edd_new_user_notification', 10, 2 );

}