If you already have Adobe Application Manager installed, you can simply open that and install Premiere and Audition. However, in case you have not install Adobe Application Manager, you can login to creative.adobe.com and download Premiere and Audition from there.
You should use the Adobe Installer/Uninstaller to remove applications rather than manually deleting the application file. Adobe applications have a lot of other components in other locations. On a Mac, for example, you would find those in your home folder > Applications > Utilities > Adobe Installers. Try running the uninstaller for Creative Suite 6 and select to uninstall Premiere and Audition to remove them. Then redownload the applications.
What Steve said is actually correct. So run the uninstaller for CS6 and then use the Adobe Creative Suite Cleaner Tool: http://www.adobe.com/support/contact/cscleanertool.html and delete the reminents of the installation.