Guess again.It's an odd situation with 18 and 19 year olds that are still in high school. While they're adults, schools still need to show parents records and adhere to their wishes. That only changes if the student is legally emancipated. I'm not saying that's what it'll take, but there's a lot more gray area to this than, "They're 18 and can do what they want." It'll take some puzzling out as this continues to develop.
Understanding privacy rights in school
Explains students' privacy rights and how to access their school records.
"Once you’re 18 or graduate, you’re entitled to see both your permanent and temporary record, and your parents aren’t entitled to see anything."