Just launch any of the CS products in the suite (Photoshop, Illustrator, InDesign, etc.) while your computer is connected to the Internet, and then do the following:
* Go to the Help menu and select 'Deactivate...'
(if the option isn't enabled, give it a minute and try again)
* On the dialog box that appears, click 'Deactivate'
* Done. The entire Master Collection Suite is now deactivated.
You can now install and activate your Master Collection on your second computer.
NOTE: Please be aware that this feature exist to help users move their licenses among their personal machines. However, there is a limit of 20 deactivations for a given serial number (the reason is because unfortunately, we detected the feature was being abused by some to "float" the license among more machines than what the end-user license agreement allows).