In the Nintex Forms Ribbon, click the Live Settings button.
Check the Publish to Nintex Live box. Another checkbox will appear, Allow anonymous access. Check this box.
Click Publish in the Ribbon. You will see a list of all the layouts your form is configured for. Click Publish to confirm.
The URL to access the Nintex Form anonymously will be provided to you once you confirm publishing. This URL is the same for any layouts you publish the form to. For example, since I created a form for desktop and smart phone, I can access the form using the URL on both devices.