Welcome to the forum, Seadog.
You've got a spade rudder "in a skeg" according to the data sheet. That means that the rudder has a foot that the rudder post fits into. The foot will be bolted to the skeg, with the bolt heads undoubtedly burried under a bunch of
bottom paint, so You'll have to go digging to find them. Once you've removed the foot, the rudder shaft comes out the bottom. You'll need to loosen/remove everything that clamps onto the rudder shaft at the top, mainly
steering gear, to let this happen. You may also have to dig a hole in the ground under the rudder to give the shaft enough space to clear the bottom of the
hull.
You have a busy Saturday morning ahead of you. Good luck with it.