I want to move out at 18 years old, but my parents say that they got the court to make it where I cannot move out till I graduate highschool, my question is can they actually do that or is it just a lie?
They lied to you. Unless they took you to Probate Court and had a hearing and imposed a guardianship claiming your inapacity, and you would know that from the court papers they served you with, the answer is no they didn't.
You are free to make your own bad choices at 18, but you better think long and hard on what you are going to do, where you are going to live and how you are going to pay all the bills you will have (many you don't even know about yet). If this is over the dog in the other question, it would be a very silly and immature reason to try to move.