Sometimes the axle will pop right out, sometimes it doesn't. When it doesn't, I think it is because the snap ring gets a little out of alignment or something. I have removed many, many of these axles and 95% of them pop right out, but sometimes it binds up and I have to really wedge something in there to get it to pop out and it usually ends up breaking the snap ring in the process...which is why I think the snap ring gets a little out of alignment somehow.
If the axle doesn't pop out fairly easily, when you wedge something in there to pry it out, remove your pry bar and try spinning the axleshaft, to get the snap ring to shift positions and it might pop out easier. When it pops out easy, a 12" flat screwdriver is all that is needed to pry with.