The lower one is the same but it's an absolute censored to remove. Loosen the bolt (drive side I think) a couple turns and give it a sharp tap with a plastic hammer and it should move.
Try to support the frame well before you do that. Your frame might be a bit crooked like mine was. We had the same problem with a mates Intense which wasn't even close to straight.
I would take it to a good shop. Either they will do a good job and save you damaging your frame. Or if they do damage the frame they are responsible for putting it right or replacing it.
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Mine goes in a a out just as easy as the 2 other pivot pins.
Pop down screw fix and get a nice 2 inch or so bolt the same thread. Wind it all the way into one side and give it a good hit with a mallet.
Bolt will be supported by the full thread inside so shouldn't damage anything if you are careful.
If anyone thing does go wrong, CRC keep the axles sets. http://www.chainreactioncycles.com/mobile/nukeproof-mega-am-main-axle-kit-2013/rp-prod104825