There are a couple ways. You can use a tool called a pickle fork but it needs to be properly sized and if not careful it can rip the rubber ball joint boot. The other way is to apply pressure with a pry bar between the spindle and the a-arm in the direction the ball joint comes out. With pressure use a heavy hammer to give it a solid hit on the spindle were the stud wedges into the arm and it will pop it out. This to can cause damage if not careful also.
Both methods require raising the front of the sled so the ski is hanging.
Pickle fork.
This method is easier with two people. I used my foot to apply the pressure which is somewhat akward.
