2001 Oldsmobile Aurora

My mother came to me and said her 2001 aurora is making a noise that sounds like a fan belt. I noticed that the crank drive pulley is kinda not running true.
That caused the belt to squeek as it travelled by Upon further inspection I noticed that it looked like rubber gathered on one side of the pulley and a space was on the other. I have never seen a two piece pulley before however I guess that is what it is. My question is however, what is the best way to remove that pulley so I can replace it with a new one? Which direction does the bolt loosen and how do I keep the pulley from turning the motor over?