The red-head Bell & Gossett zone valves permit removal of the actuator portion without draining the system. If you can see curved wires under the head, these are meant to be squeezed together to remove these clamps from a groove around the valve head.
If water is now dripping out under the electric actuator head then you could be burned by the water.
If the valve is dry, the valve seals are holding the water inside. When you remove the actuator the valve will be in the open position until you replace the actuator head.
If you are worried about this, get someone with experience to remove and replace the head for you.