There are many ways of separating the lower arm outer balljoint from the hub but I've used this one for years. Just put a spacer in between the hub and the balljoint and use a screwdriver to push the balljoint shaft down wedging the screwdriver against the raised edge on the hub.
Doesn't need much force as you are pushing directly down on the shaft, it pretty much falls out. Turned down a few different thickness spacers from some scrap so I can add them as the shaft drops.
