How to deauthorize?
How do I deauthroize if you no longer have the computer to do so - and still need to access your iTunes?
If you no longer have the computer(s) you want to deauthorise,
Log in to iTunes, go to "view your account info" on the itunes store, deauthorise all five, (Please Note: this can only be done Once every 12 months) and then re-authorize your current Computer(s) one at a time.
Authorise / Deauthorise About