Not Sure why you want to disable but this should never be an option rather than a workaround. How would you power on a host physically assume after power outage at DCs? Power Button is required many times to hard reset host when its hung from GUI and SSH, Power Button is required when you perform hardware troubleshooting/installation.
From Data center perspective this question is not possible not because H/W vendors can't do it but this is an important requirement . For security point of view that's why Data Centers are secured and isolated places where servers are kept in locked racks..