You may have needed to uninstall office but ran into problems that prevented you from completing this task.  Well I ran into it and finally found a solution to allow me to install the latest version of office without the installer blocking it due to it detecting a preview edition being installed.

The first thing I did was use the Programs and Features to uninstall all Office Products.  This appeared to go very well as I no longer saw it in the Programs List.  So I attempted to install Microsoft Office 2013 Plus and it detected I still have it installed even though it was no longer listed in the Programs List.

To resolve this issue I renamed all instances of Microsoft Office to Microsoft Office.old in Program Files and Program Files (x86).   I then proceeded to ran the Windows Install CleanUp Utility to remove any instances that may have been left over from the uninstall.  I did get a few errors when I tried to run the uninstaller for Office Preview 2013 Plus so I ran the following command from and administrative command prompt:

%windir%\system32\secedit /configure /cfg %windir%\inf\deftbase.inf /db defltbase.sdb /verbose

Finally I proceeded to run CCleaner to remove instances of OFFICEXX with XX being the number ( make sure you back up your registry before applying fixes).Once this process was complete I launched the 64 Setup for Office and it installed without any problems.