How do you password protect a form?

Unfortunately, this feature is not available as such, but as a workaround, you may use conditional logic to show/hide the fields if certain value is entered in a field, it would work like a password; however, kindly avoid using the word "password" on your form since it will trigger our anti-phishing system. 

This guide will help you showing/hiding multiple elements: https://www.jotform.com/help/297-Show-or-Hide-Multiple-Fields-at-Once-Using-the-Section-Collapse-Field 

I hope this helps.