Moving out at age 18?

So my parents and I have been fighting a ton lately and When I turn 18 I want to move out. I already have a place to go and work 2 jobs so everything is taken care of. I was so excited to turn 18 (which is only a month away) and my mom said that they talked to their attorney today and he said it didn't matter if you were 18 or not, but you can't move out until you graduate high school? Is this true? Please help me, I live in Utah