Every time you uninstall Office 2010, there are residual files that are being kept in Windows registry and other folders. It is crucial to delete these keys or files before you re-install Office. If you are trying to re-install a trial version, you will most likely get an error. The installation will just keep on rolling back. Remember, you will not be able to re-install the same trial version and product key ever or else you’ll get an error 25004. The best way to override this is to get a new full product key or ensure that all residual files connected to MS Office are deleted.
Before you attempt to uninstall MS Office through Control Panel, read this KB article from Microsoft. The 5th step is deleting registry keys associated to Office 2010. The two most important keys to delete are these:
If you are using Windows 7, you may go ahead and delete these keys right away. However, if you encounter this error: cannot delete office: error while deleting key. You need to take ownership and grant full control of each key first. Here’s how:
-Right click Office registry key
-Select Permissions – Advanced.
-Go to Owner tab.
-Select username or administrator then click Apply – OK – OK.
-Right click Office registry key again.
-Select Permissions – Advanced
-Uncheck Include inheritable permissions from this object’s parent. Choose Add.
-Still under Permissions tab, highlight your account username.
-Click Edit… button
-Allow Full Control by putting a check mark in the box provided. Click OK
-Put a check mark on Replace all child object permissions with inheritable permissions from this object. Click Apply.
-If a Windows Security dialog box pops-up, choose Yes. Click OK-OK.
Now after doing these steps, retry to delete the 2 registry keys.