How do I deactivate iTunes from an old Laptop

Hello,

Does anyone know how I can deactivate iTunes from PC's or Laptops I no longer have? I understand that iTunes allows you to activate up to 5 computers and you can manage them by activating and deactivating them. The problem I have is that two of the computers I use to own crashed and one was stolen and so I wasn't able to deactivate those accounts. This now only leaves me with 2 computers I can activate iTunes on. Is there any way to deactivate an old computer? Or is my only alternative to set up a new account?

Any help would be greatly appreciated

Thanks,
Jim