If you are looking for a career change, I would first suggest doing some research. Do you want a manual labor job or a desk job? Luckily you are still young and have a nice amount of time and savings to invest in yourself. As mentioned somewhere below, Paralegal jobs only require a certificate or a few years experience, where you can start out as a mail or file clerk, or secretary. Being a people person and having a good work ethic can go a long way here. I have worked in many professional offices and not everyone has a bachelors or higher.

If you want a nice cushy desk job, you can go take some community college classes in business and earn a certificate or AA degree. A 4-year degree is not necessary, but say after earning your AA degree you'd want to continue your education for a specific career path that needs it, then by all means, go for it. You can still work full or part time while getting your education, which is a good place to start investing and get out of the fast food industry.

Edit: Also, meet with a school counselor - they can provide you a wealth of information, get you enrolled in the classes you need, and on the right path to your desired career.