Couple of things.
First, when did it become crooked? Did you first verify that the steering box itself is centered precisely? This is the first thing to make sure of. All other aspects are taken from the box outward.
Next, if you do still need to re-orient the wheel, that yoke/universal joint down at the box in your picture is an aftermarket unit. The set-screw with jam nut at the base (closest point to the box) should be just a simple set-screw. Not an all-the-way-through bolt.
Loosen the nut, loosen the set screw, then pull the shaft away from the box.
It's possible there is another one 90 degrees from this one, but if I'm not mistaken there is only the one.
A key point of safety here though, is to not put it back together without applying thread-locking compound to the screw and nut. This is one thing on a vehicle you do NOT want coming loose! There was a thread about that here just last week in fact.
When all is said and done, there's nothing that says you can't re-orient the steering wheel either with the shaft at the box, or the adapter up at the wheel. But there is a proper way to do it, and that is to make sure that the turn-signal canceling aspect of the steering wheel is still properly set up. After all, you don't want to go through all that work and find out your signals cancel as soon as you move the wheel in one direction or the other.
But the over-riding bottom line to all this is to make sure that all adjustments are made with the steering box centered. This way, once you're done and on the road, if your steering wheel is not centered then you know that the box is not either, and you won't get the best steering feel/handling characteristics until you adjust the draglink to compensate for a lift, or linkage change, or whatever is going on.
I know we're talking about your rig in other threads, but I can't remember all the details. Such as amount of lift, whether you have an adjustable draglink or not, and stuff like that.
I seem to remember you've installed a trackbar drop and a pitman arm? Or is that someone else I'm thinking of? If it's you, all the more reason to make sure that the box is centered before doing anything else.
Good luck.
Paul