Talk to the principal. In many schools, the principal makes the decision regarding vending machines. While he may want to remove the machines, the revenue from the sales goes back into the school. Be ready to offer alternative sources of revenue. Look at other fundraisers such as book sales, school fairs or community-wide benefits.
Organize other parents. Compile data on childhood obesity. The Centers for Disease Control, National Institute of Health and a wide range of children's hospitals all recommend limiting soda for children. Show the evidence linking high fructose drinks to childhood obesity. Write a short flier with data highlights and send it to other parents. Bring them together for a meeting to discuss the presence of soda machines.
Write a petition. Once the parents are organized, arm them with copies of a petition aimed at removing the soda machines. Send them to contact parents they know to create a grassroots movement.
Present the completed petition to the school board. Ultimately, the school board has the power to ban soda machines from any, or even all the schools in their system.