What is the steps in replacing a lower control arm in 98 Chevy blazer?

Disconnect the ball joint. I believe on that vehicle its pressed into the lower control arm, if it is then the new control arm should come with a new one, but if not then buy a new one and install it in the new controll arm. You can use the old one but you might as well replace it while you've got all your tools out. After the ball joint is separated from the steering knuckle, undo the bolts that hold the control arm bushings to the frame, and the control arm will come right out. (Will likely take a few good smacks from a heavy hammer to get it to come loose) Watch out for any sensor wires that are clipped to the control arm- dont want to cut/smash them.