Answer:
When anyone in the US turns the age of 18 years old, regardless of whether they are in school or not, they are now considered an adult who is able to make their own decisions pertaining to their life. You are now responsible for your own actions/choices, whether they are smart ones or not all depends on you.
Your parents are not legally responsible for what you do anymore. They can however help you come to make a choice they feel is in your best interest. They are likely much more experienced with how things are in the world than you are, so I'd recommend you at least listen to what they have to say about it, before you jump into making a decision you may regret later on.