Str8vaping should be able to chime in, I know he's had a few provaris apart. Also cba191, he took a mini apart to paint it. Basically, you need to have a thin but strong rod you can move past the electronics in the tube. Rest it against the bottom of the top cap and use a hammer to tap out the top cap, going around the edge of the cap as you're tapping it out. I believe there are a couple wires connected to the top cap, so keep that in mind. Also, the board with the electronics is glued into place in the tube, so when you start tapping out the cap, those spots of glue will probably break and come out. Make sure to glue the board back into place when you're re-assembling.
I should say that I've never personally disassembled my provari, but almost did after getting some assistance from the folks around here. I just ended up letting Provape deal with it, they did a great job and I got my baby back in short order.
P.S. There's also a youtube video that shows how to take a provari apart, although it is in Spanish I believe.