Northern Territory DISCHARGE NOT ALLOWED if you are 18 years and over.
Northern Territory, Adoption of Children Act
Part 3–Adoptions Under This Act, Division 6 — Adoption orders
44 Discharge of Adoption Orders
(2) The Court shall not make an order discharging an order for adoption under this section if it is satisfied that:
(a) the child has attained the age of 18 years …