How do you quit a job you just started?

Because its a work-study position its meant to be a job on the side that allows you to work to help pay for some of your education while still allowing you time to study. I would keep the job, despite not enjoying it as much if it truly allowed me to do homework and not affect my school work. I'm more concerned with the part of your question where you mention it is affecting your school work. I'd be careful around that. Federal funds are granted to you on an academic calendar, so they will remain there for the semester if you don't use them up. If you decide to leave the job, then the funds are then gifted to other students in dire need of the funding instead. You could ask for less hours if school is getting too stressful, anyhow you should be working a maximum of 10-15 hours. Just remember to re-apply for work-study if you quit. And if you do quit, since its work-study, you can say that you need more time for your academic work and would like to be considered in the future for when there is more down-time, as in after finals week. Usually students can work up until the holidays commence, so if you are done with your last and final exam, you could even work more than 20 hours and rack up on the dough!