The screw on the knowb will not loosen up but turns the knob and water on... any idea on to loosen it up and remove the knob?

Use WD-40. Soak it wet. Let it stand over night. Use large, long Phillips screw driver. Push as hard against the screw as you can and turn CCW to break the grip.

I'd do what Milo suggests. I sometimes put the driver handle up againist my chest to push and then grab the handle with a channel lock for leverage, lefty loosey