Specifies whether a file, assembly, or project output group should be removed from a target computer when the application is uninstalled. By default, all items are removed during uninstall.
The settings for the Permanent property are:
The selected item is removed when the application is uninstalled.
The selected item is not removed when the application is uninstalled. It remains on the target computer until it is manually deleted.
The expected behavior is that uninstalling an application should remove everything that was installed by the application. Make sure that you have a good reason before setting the Permanent property to True.