You could consider to hide it using CSS (display: none;). Using the developer pane you can determine the button's CSS properties "class" and "id" ("setting button" resp. "settingsButton") and use that in the form's Custom CSS.

Thanks Jean-Pierre,

Yes, this is the exact solution that Nintex customer care offered (I don't know CSS, hence I didn't know to use it :))

This is what they said:

The Settings button is by design inserted to allow for users from different time zones to fill the form and submit it correctly (especially if you have a date/time control).

The workaround to hide the settings button is to add the following code to the form Custom CSS:

.settings.button {

display: none
!important;
}

Good to hear Jacquie Annand,

In the Form's Settings you'll find the Custom CSS settings. Just add the mentioned code at the top in front of the other code.