In my opinion it’s a best practice to hide the sites left navigation or current navigation from all Nintex forms. The reason why is if someone clicks on a left navigation link while filling out a form, all the information they entered into the form will be lost. So to prevent that we just hide the left navigation from all Nintex forms:
How to hide the left nav from forms
1. Open the form in the Nintex Form Designer
// Hide the left navigation
4. Save the Settings and Publish the form.
Finished Example: The form will now open with the left navigation hidden: