Can't finish the Excel Add-in uninstallation.
The Excel Add-In is an .msi file that is installed to your desktop. This file is required for the uninstaller to run.
In order to un-install the Excel Add-in, use the Windows Control Panel, select the Add-in and click Uninstall.
If you do not have this required file then you will not be able to complete the uninstallation.
You can get the file from the Install help page: