Int 21 Fn 5F4E  u - LAN Manager Enhanced DOS - Dosdeletemailslot           [N]

   AX = 5F4Eh
   BX = handle

Return: CF clear if successful
       ES:DI -> memory to be freed (allocated during DosMakeMailslot)
   CF set on error
       AX = error code

See Also: AX=5F4Dh,AX=5F4Fh