I've found this solution / works fine for my 1.6.1.4
https://stackoverflow.com/questions/38916902/prestashop-disable-contact-form
I used 3rd advice - separated module - code works fine, just need to add <? in the beginning and ?> in the end. After you copy contactpagedisabler.php file in modules/contactpagedisabler - you can find it as:
Contact page disabler v1.0 by author named "whatever", then just enable it.
nc