How do I take off the whole windshield wiper.

For minivans, pop the plastic cover up, remove the 15mm nut, use a wiper arm pliers to pry the arm off the splined shaft. Place a rag on the painted surface first if the pliers doesn't have a protective rubber coating.

Most full-size vans have a small hole on both sides near the pivot. Raise the arm, then slide a small finishing nail through those holes. That will hold the arm up and allow you to use it as a lever to wiggle it off.

Some have a tab that moves sideways a little after the arm is raised. That will hold the arm up so you can wiggle it off or use the pliers.