Old reqirements cant delete

Hi, Expert,

My client use PP module without MRP, But now they want MRP , I delete almost all old requirement , TECO for the prd order, but some , but some old subcon requirements is there, which consumed the stock? my client wants to delete all kind of old requirements , I cant delete . I send you 3 screen shoot regarding the issue. what happening, when I open the requirement from MD04 it shows zero open quantity ? Need your help.