Windshield Wiper Switch Removal 1988 GMC S15
 

What inside the steering column holds in the actual switch portion of the windshield wiper switch?

I'm not exactly sure what holds the arm in place. In my experience it's a pin.
To remove it will involve dropping the column down to reach the harness plug.
This is the best illustration I could find.
Thankfully you don't have any air bags to deal with.

Attachment 1858