If you do not have the Title field in your Nintex form, all your form entries will be displayed as ‘No Title’:
The problem with this is you usually need the Title field to display on your list views as it’s the only column that provides a link to the form itself, including the edit menu options (the ellipses), and the title is what is shown in search results. So if all your forms are titled No Title, no one will be able to tell which form is which when searching.
Often it doesn’t make sense to make an end user put in a ‘Title’ for the form, instead what we usually recommend is creating a Calculated value to create a unique meaningful title for the form based on values entered into form fields. See the Creating a Form Title tutorial for complete instructions.