To Un-Install BarrelTime, go to the Control Panel and select "Programs and Features:"
Select BarrelTime from the list (the icon may or may not show). Right click, then select "Uninstall."
As of this writing, the UnInstaller leaves a few crumbs behind. To remove them, use File Explorer to look at the root drive "C:", if there is a "C:\Sandune" folder, delete it. Depending on your administrative permissions, you may have to go to each sub-folder first to delete the few left-over files.
The UnInstaller seems to remove all of the application/program files. You can double check by looking for a "C:\Program Files (x86)\Sandune" folder. If it exists, delete it.
Finally, BarrelTime uses the Borland Database Engine (BDE) which is located under the "C:\Program Files (x86)\Common Files" folder. If you are sure that the BDE is not used by any other application on your computer, and there are no other folders other than "BDE", the "Common Files" folder can be deleted; if there are other folders under "Common Files", the "BDE" folder can be deleted.
Warning: Deletion of the "Common Files" or "BDE" folders can cause other programs/applications on your computer to stop working. Be sure they are not needed by another application on your computer before deletion.