How cold would a freeze ray have to be in order to freeze solid an entire red Super Giant Star instantly? :D?

There's no such thing as a freeze ray. Cold is really just the absence of heat, like space is the absence of matter. You can't make heat just disappear, it has to go somewhere. You'd have to transfer all the heat in the red giant star to some other object, or let it radiate away.

red super giants are the coldest stars in the universe

they get that way shortly before entering the white dwarf phase

also there is no such thing as "cold"

there is heat and less heat

even if you are talking about it in that context, the most effective way to end a star's life would be to disrupt its fusion processes, siphoning energy from a star would be ridiculous

the answer depends on the mass of the star which determines how large the star has to be to prevent itself from collapsing in on itself

You would need to lower the temperature to absolute zero. This is quite impossible.

VERY cold!!!!