2 possibilities here:
1) It's got a short piece fixed to the main "tiller" with 2 bolts into the cast part, I think so you can change from a single to double hole attatchement for twin engine setups.
2) it's a one piece cast arm, and you'll need to dismantle half the engine to get it out as it;s welded to the top of the tiller tube.
Have a look just behind the bit whetre the steering link arm connects. If you can't see 2 bolt heads,
Having said that, even if it is a bolted 2 part one, if it's that corroded, chances are the bolts are going to be stuck fast, so probably easier to theow it at a dealer........