You say you "never finished" your degree. But did you start it? If so, how far along did you get in college?
24 is still pretty young; I wouldn't let your age stop you. But if you're going to finish your medical degree before you're ready to retire, I'm afraid that means you're going to have to go to college full time, and that means dropping your digital marketing career, or at least cutting way back on your hours (20 or fewer per week) while you're an undergraduate. And you cannot work at all once medical school starts, if you have any expectation to pass your medical school exams and your USMLEs.
You can be any undergraduate major for medical school, as long as you take the medial school prerequisite classes (which vary a bit by medical school but typically include two semesters of general biology with lab, two semesters of physics with lab, two semesters of general chemistry with lab, organic chemistry with lab, biochemistry, English composition, and calculus or statistics. Even if the medical schools don't require it, psychology is tested on the MCAT so you might want to take a class in that as well.) You could major in marketing since you're familiar with the subject; the objective is to get the highest grades possible.
Community college is not your best option, if you have two or more years of college under your belt already. Medical schools do not look favorably upon prerequisites taken at community college; at least, if they're out of sequence. What I mean is, if a student takes the medical school prerequisites at a community college in the typical course of a 2+2 transfer degree, that's fine, but if it looks like an applicant took the prerequisites at a community college instead of at a four-year college because they're easier at CC, then medical schools will be skeptical of your abilities. Assuming you already have some college, and it was at a university and not a community college, your going back to community college now to take the prereqs would raise red flags to medical schools.
So the next steps are to drop back in to the college or university you originally attended, or apply to another one (as a transfer if you have taken any college classes after you graduate from high school; otherwise as a freshman). Try to keep it cheap; you don't want $100K in college loans before you even start medical school. Apply for all available financial aid; you will need to strive for an A- average (at least) so you won't be able to work full-time to afford living expenses. If you decide to go back to college, cut down on expenses as much as possible (find a place to live close to campus; sell the car if possible, downgrade if not, etc.)