>don't have serial numbers for this anymore nor my original CS6 software
https://www.adobe.com/account.html for your Adobe orders page to find your registered serial numbers
previous versions http://www.adobe.com/downloads/other-downloads.html
-when you have your serial number and CS6 via download be sure to copy everything to a USB hard drive as a backup
Below MAY work to remove the CC information... I do NOT know what it will do to CS6
-http://helpx.adobe.com/creative-cloud/help/install-apps.html (and uninstall)
-using the cleaner after uninstalling and before reinstalling will usually help
-http://helpx.adobe.com/creative-suite/kb/cs5-cleaner-tool-installation-problems.html