Let them run it while you finish school. Many 18 years old get in a jam by moving out too soon. They don't think it cost much to move out. Use this time to learn how hard it is to live on your own. Here is a list of things you do if you were living on your own:
Laundry, cooking, cleaning, throwing out the trash, paying rent, paying electricity, paying gas, paying insurance, paying cable, paying cell phone, paying for internet, buying clothes, buying food, buying furniture, buying a computer, buying a TV, buying a stereo and many more.
This is just a short list of the things you need to do to live on your own. Add each of them up and you will see that you need a good education to make it on your own.
Don't rush. Just learn from your parents. They want you to do good and that is why they are telling what to do. I did not like it either when I had to let them run my life during school.