How do you change 2001 mercury grand marquis windshield wiper arm?

Answer 1

Do you mean wiper arm or wiper blade assembly that's attached to the arm? Most people mean wiper blade so here's your answer:

The 2001 Mercury Grand Marquis has the most common hook-end wiper arms. See sources and related links below for installation videos. Also, purchase the replacement blades first and there will be additional instructions/illustrations on the replacement packages. Locate and press the tab or button where the wiper blade is inserted into the hook of the wiper arm and pull wiper blade out of hook. You may have to rotate and flex the blade to make enough clearance for the hook to pass through.