I've always seen on TV, they unscrew, but it's important to count the number of turns to take it off, and only screw the new ones back in that name number. They tighten against another bolt to secure them. To remove them from the ball socket side, you'd need a ball joint too (looks like this)
Where you place it between the ball joint upper portion and what it's going into...then hammer that wedge in there (rubber mallet preferred) and it will pop the joint out, then unscrew (count the number of 360° turns). Reverse for reinstall (you'll need something to pop the ball joint back in)
That's my $0.02