I did a bit of digging around as the post by Guest Blogger Alpesh How To Manually Uninstall Office 2007 Beta has become one of our top posts. I thought I’d also provide an alternative provided by TechRecipes when you cannot uninstall Office 2007 Beta From XP or Vista.

1. Make a System Restore and/or Backup. When trying to fix Office installations, you could knock out other Microsoft associated programs. You should also backup your outlook files if you want to save your old address box and mail. Here is the manual way to backup your outlook information. However, this automated outlook backup tool from microsoft is better.
2. Clean out the temporary file areas with Disk Cleanup (Start Menu -> All Programs -> Accessories -> System Tools -> Disk Cleanup) Make sure you clean out log files, dump files, installation files, etc.
3. Install Windows Install CleanUp. Save the utility to your desktop. You will need administrative level to install it. In vista, you will need to right-click on the setup file and select Run as administrator. Select all the office installation entries and then click the Remove button. Click Exit when done.
4. Now you can uninstall Office 2007 Beta as you typically would from the control panel. At this point, the program is uninstalled; however, there are still a ton of office related files in the office directories. You can try installing the official, retail version of office 2007 at this point if you wish. I would try to clean out these directories first. Office typically lives in here… C:\Program Files\Microsoft Office. Some files may be system protected and be difficult to delete. I have not found that jumping through all the hoops to delete these are needed.

These techniques solved our various problems with uninstalling office 2007 beta. I hope you guys will find them useful.

Source: Cannot Uninstall Office 2007 Beta From XP Or Vista?