Welcome to Bonneville Club! I like your name
It has been too long since my '87, but If your wipers are like the newer ones on my '95, you need to lift the blade up a few inches off the windshield and while holding it there, slide the little lever out on the base of the the arm where the arm attaches to the post. You may need to pry it with a screwdriver. It looks like a little tang. When the lever is out, release the arm and blade; the tang or lever will hold the spring tension and keep the arm and blade off the windshield. You then simply lift straight up on the arm to remove it from the post.