Is it possible to prevent the thermostat from being adjusted on the alarm panel?
Is this on an IQ Panel? If you want no one to ever be able to adjust it on the panel you can disable the thermostat page under Settings > Advanced Settings > installer code > Installation > Installer Settings > Thermostat Page.
If you just want to stop people without a code from doing it you may be able to use the screen lock feature. This is under Settings > Advanced Settings > installer code > Installation > Security and Arming > Screen Lock.