Radiator drain plug

Have a 98 LTZ and I'm trying to replace the antifreeze. Now I know this sounds stupid, but how do you get the drain plug to open? It's white plastic, I tried turning it but it's not moving and I don't want to snap it. Is it screwd in or pushed in?

Welcome to AF, counterclockwise 90 degrees and pull out gently at the same time. Even better, disconnect the lower hose.