Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Try running the fixit from www.support.microsoft.com/kb/971179
You can also try the steps mentioned in www.support.microsoft.com/kb/928218
The steps mentioned in the above articles are to uninstall office 2007 programs manually from the computer when you are not able to uninstall them from add/remove programs window.
Note: Make sure you have the disc & product key for office 2007 before you uninstall it
Please do not forget to read the disclaimer mentioned under step 5 in the article before making any changes to the registry