How do I disconnect it from the steering box?

In stripping down the interior I have the column unbolted from the firewall and could easily pull it out but I am not sure how to disconnect it from the steering box.

To be honest, my box has a leak anyway so I may just go ahead and replace it too when I get the column out.

I did a few google searches and I see that there is a rod with splines that comes out of the gear box but I assume there is a button or retainer that I need to remove first before I start banging on it with a deadblow hammer!