My computer recently crashed, deleting all current things I have installed on my computer, one of them being CS2. I managed to buy a new computer, seeing as the old one would never work again, but I need to download CS2 onto my new computer for a class. But, I have a feeling that my CS2 is still activated on my old computer. How do I de-activate it?
You should be able to activate on your new computer given that you have only activated CS2 on one machine. If you had already activated on another machine (for a total of two), then you should contact customer support and explain to them that one of your machines crashed - they should grant an activation overrride for you.
If you ever re-install a new OS on the machine that crashed, if you activate CS2 on that machine, you will not be decremented and activation allocation because the Adobe Activation server will know that that specific machine had communicated with it before. You can then deactivate after a successful (re)activation.