You don't "have" to go to college. College is not for everybody. If it is not something you are interested in, don't feel bad! You can go to a trade school, or simply work. I know lots of people in construction who make really good money, without ever having gone to college. But, it is physically demanding work, and once you get to be about 45 or so, your body starts to feel all the aches and pains!
Anyway, if you do go to college, you "have" to go until you finish! An Associate's degree is 2 years, and a Bachelor's is 4 years, IF you go fulltime and IF you pass all your classes. If your heart is not into it, it will not be easy to pass the classes. This is because (1) they are hard, and (2) there are too many distractions - things you can do instead of studying!
College is not free. It is expensive. If you are not too sure, I'd recommend you go to a community or Junior college first. They don't cost as much, and it will help you to decide whether or not this is for you!
And if you are not going to go, I strongly encourage you to explore other career options, either on this site, on-line, or with a counselor. It's important to have a general idea of what it is you want to do with your life!