What changes when you turn 18

Rotate treats anyone under 18 as a minor, and a few things change automatically on your 18th birthday.

Steps

Nothing to do. It happens on its own, from the date of birth on your record.
After your birthday, open Messages and you will find Message a coach now available to you.
If you want a parent to keep following your progress, ask your coach to invite them again.

Every approved parent link expires at 18. From that day they see nothing until you choose to have them re-linked.
Your parents are given notice roughly a month before, so it is not a surprise on the day.
Before 18: no private one to one thread with a coach, and session reminder emails go to your parents rather than to you. After 18: both are yours.
Nothing of yours is deleted. Your history, assessments and messages carry on as they were.
If your date of birth is wrong on your record, tell your coach. It is what all of this runs on.