Upper Ball Joint question

It takes a special socket.

The A body version is different than the B & E-body version which is larger, but this may depend some on model year & also if any parts were changed out in the cars past.

One way or the other, leave the A arms bolted to the car to remove the ball joint.

That will help hold the A arms in place while you break the threads loose on the ball joint.

Have the cars weight safely supported as well, you do not want it to land on you if you have to apply a lot of force.