Blot the beet stain with white vinegar and water to lift as much of it as possible from the sweatshirt. Rinse the sweatshirt in cool water.
Treat the remaining beet stain with a commercial prewash solution. Follow the directions carefully before applying the solution. Rinse the sweatshirt with cold water.
Soak the sweatshirt in a solution of oxygen bleach and water if the stain remains. Read the label on the bleach to determine how much to use not all products have the same potency.
Launder the sweatshirt in cold water. Add your preferred detergent to the washing machine.
Remove the sweatshirt from the washing machine. Hang the sweatshirt to air dry. Inspect the sweatshirt to determine if the beet stain remains. Repeat the stain removal steps until you remove the beet juice completely.