Yes....it is an adjustable steering column. Having removed more than a few of them over the years here's what works for me. Get some Liquid Wrench, WD-40, Kroil or similar penetrating oil and squirt a couple of drops onto the splined shaft close to the hub that's on that shaft. Let the penetrating oil soak it's way down the splines over night. The other advice given in another reply to this question regarding using an appropriate piece of wood to knock the locking shaft down into the center of the steering shaft works too. If you use a harder wood and not soft pine or similar, it will work easier.
At the bottom of the center shaft is an odd shaped round metal piece, tapered on one end. This is what locks the sliding splined shaft in place when the center of the steering wheel is turned to lock the steering wheel in place. This "lock" is where your sliding splined shaft is stuck. Sometimes a sharp hit to the center of the will free it ( with the hard wood piece previously mentioned). Do not use a hammer on the end of the shaft. It will mushroom the end of the shaft so that when the steering wheel comes loose, you can't get it over the end of the shaft ( ask me how I know this).
Suggestion: Take off the column covers top and bottom. You will be able to see the splines on the shaft. Put some penetrating oil or light grease on the splines BEFORE you do the other steps. This will aid in freeing the wheel from the shaft after you break loose the locking mechanism when the wheel slides to the bottom of the splines. You could also put some penetrating oil down the center of the steering shaft where the smaller threaded shaft sticks up past the end of the hollow steering shaft. The locking mechanism is at the bottom of that hole and is connected to the smaller threaded shaft. If in the process that small threaded shaft drops down into the hollow steering shaft, which it likely will, push the steering hub all the way down to where it stops and the small threaded shaft will be close to the open end of the steering shaft. I have used a magnetic tool that fit into the opening to get the shaft back up to where I could grab it. When I didn't have the magnetic tool handy, I used an ice pick to snag the threads and work the shaft up to where I could grab it. If all this doesn't dislodge the hub for you, just soak it with penetrating oil once a day until it breaks loose. Have waited as long as a week for it to work but it has always worked. I hope this works out for you.
