Can't cancel free trial under organization

My school account gave me free access to Photoshop and other services for my photography class, but the license expired after the school year ended. I activated the free trial expecting to be able to cancel it after using it once more. However, to cancel it it seems like you have to had paid for it - I am unable to access "Manage Plan" or "Edit billing" because it is under my county's subscription. How do I cancel the free trial, before someone has to pay for it?