I checked the registry after a purge/reboot and noted there was a lot of left-over registry settings. Then I installed Fences 2 and made sure that I could uninstall it without any issues. There were still a bunch of registry settings left over as well as directories on the hard disk. However, I can live with that and I consider the issue closed. Thanks for your help.
It worked to an extent. After running it asked me to complete the Fences 3 installation which I canceled. Fences 3 still showed up in the 'Programs and Features' section of Control Panel. When I tried to uninstall again, Microsoft said that it had already been uninstalled and asked me if I want to remove the reference from 'Program and Features'. However, the registry still contains a lot of references to Fences.
When I try to uninstall Fences 3 from Windows 10 64-bit I get an error message: Failed to load plugin: C:\Program Files (x86)\Stardock\Fences\Uninstall\Unicode.lmd(#1) I need to uninstall Fences 3 in order to install my registered copy of Fences 2. How can I deal with this problem? Thanks.