Right now I am a mechanical engineering major and I am going to change it to marketing next semester. I'm pretty sure I just failed my calculus final (along with pretty much everyone in the class), which would give me an F for the course. Do I have to retake it again? I don't believe it is required for marketing.
If I fail a college class, do I have to take it again if I am changing majors?
No, unless that class is required for your new major or a school requirement.
It will still hurt your GPA, but it won't be necessary for a degree.
If I fail a college class, do I have to take it again if I am changing majors?
Regarding majors, no, you do not need to retake calculus.
Regarding your GPA, I would take it again- they drop the first score, only if you do better.