There is no state in the union with compulsory education laws for minors of greater age than fifteen.
So, that means that you actually wound up staying in school at least a whole year longer than you had to.
But, don't take my word for it: simply walk into your high school office and tell the receptionist that you've decided to drop out, and that you are just there to turn your textbooks back in and obtain the final list of any fees or dues you still owe.
Expect them to tell you to go to class (it's how they get the money from their sponsors that gets them paid), and to threaten you with detention, but remain resolute and continue to inform them that the only direction you will be heading once you leave the office is off-campus.
Once they tell you that they're calling the police, is the sign that they recognize their own lack of authority to impose any kind of punishment upon you.
At that point, simply walk out.
Then, of course, I would strongly recommend you sign up at your local community college. College classes are OH SO MUCH less hellish than anything they force you into in high school. This is because NOBODY is forced to attend college, and they know that if they don't make classes worthwhile, they won't be able to keep students coming, which is how THEY earn their paychecks.
So, even though I am NOT trying to talk you out of staying in high school, I AM trying to encourage you into continuing your education. College is NOT the hell that high schools most definitely can become.
Get your GED, get an Associate's Degree, and earn some scholarships. You'll be grateful, when you do.