I just bought a new mac and I tried to associate it with my itunes id but I apparently already have 5 computers associated with this id. I was reading some info that if this is the case then I should deactivate all computers associated with this ID; however, there is no info. on what will happen/to do thereafter. I am concerned that I will have to wait 90 days before reconnecting?? Does anyone have any experience with this plan of action and details on what to expect after deactivating my id from all devices?
Welcome to the Apple Community.
You can't (only) de-authorise computers you no longer have access to.
Your only option is to de-authorise all your computers and then re-authorise those you wish to be authorised. You can do this by logging into your account settings in iTunes on your computer (Store > View My ID) and selecting the option to de-authorise all.
Please note however, you are only permitted to do this once in each 12 month period, therefore you would be better de-authorising your computers before you lose access to them. you can do this from the 'Store' menu in iTunes.