If you have a concern about PHI or other concerns of saving data on your SQL database of the Ninja Forms follow the step on their site http://docs.ninjaforms.com/customer/en/portal/articles/2045697-faq#faq_save on the save-sub.php file.
The save-sub.php location may vary based on your operating system but if you are on a UNIX based system and have access to SSH you can try this command to make the change easier.
sed -i 's|$save = true;|$save = false;|g' /var/www/html/wp-content/plugins/ninja-forms/includes/display/processing/save-sub.php
If you need to re-enable it
sed -i 's|$save = false;|$save = true;|g' /var/www/html/wp-content/plugins/ninja-forms/includes/display/processing/save-sub.php
Last Updated on December 21, 2015