Verified answer

Sometimes you can use a punch to push it sideways and then yank it out with vise-grips. Sometimes it's easy. Usually it's hard.

You didn't say if the engine is out or not. If it is, just get a good size punch (3/8 or so) and hammer and hit the plug near the edge to get it to turn in the bore. Then grip it on the high side (away from where you hit it) with a pair of channel-locks and pry it out. If the engine is still in the chassis, you are possibly going to run into some clearance problems. Some plugs just cant be removed without pulling the engine.

Tap one side in with a punch or screwdriver and a hammer. It will spin around where you can grab it with pliers

if you have room just drive a screwdriver through the freeze plug and pop it out.

Why? Is it leaking? You can just pop them out. Drill a hole in it, put a screw in that hole and pull it out. However, if its not leaking, don't mess with it. They are hard to get back in and sealed well.