A "light switch" in a guest bedroom controls my attic fan.

The fan operates on a thermostat. So, it only goes on in the warmer
months. However, I am getting tired of guests continually flipping it
on and off.

So, I thought, what about putting a blank wall plate there. But, how
do I "fix" the wires so the current will be on all the time? Or, is
that a no-no (don't know why it would be, but...).
tim