If you tried to uninstall the Office 2013 Preview and it did not properly uninstall or it left a lot of bits lying around, Microsoft has a an uninstaller for the Click to Run version. They also have instructions for anyone who prefers to uninstall Office 2013 themselves.
Details can be found at How to uninstall or remove the Microsoft Office 2013 Preview suites
After uninstalling Office, you should reboot then do a reinstall of your old version. If you used your old profile with Outlook 2013, you should also make a new profile.
Because Outlook 2013 moves the Profile keys, uses a more compact *.ost format, and keeps IMAP mail in an *.ost file, profiles created in Outlook 2013 won't work with older versions and profiles used with Outlook 2013 may result in errors.
(The new profile key is HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Profiles.)
Published October 2, 2012. Last reviewed on October 2, 2012.