How To Replace Water Tank Drain Valve?

My fresh water tank is leaking out the drain. I assume the knife valve is no longer “tight”. Can I simply remove the 4 screws around the drain outlet and pull the valve assembly out? I’m not sure what holds the valve to the tank. The valve assembly isn’t fastened tightly to the tank, it will move around some if I push/pull. There is a lot of spray on insulation on the back of the valve, in the little space between the valve and the tank.