For those whose account was created as a child account through the Manage Family Account process, that profile will be automatically removed upon the child's 18th birthday. The Manage Family account administrator will receive notice that the child has been removed.
If your child wants to continue to have their account managed by the account administrator, they will need to create their own account with a unique email address. Then, the family administrator will need to send a new invitation to the newly-turned adult. Once your child accepts the invitation, you will then be able to resume managing their prescriptions.