Forcefully removing the 'Installation Directory' during uninstallation..

Most frequent defect that is logged against an Application Package is around "the installation directory not deleted during uninstallation" and we all know that based on Windows Installer design, the files / folders that are not created by the installer will not be removed by the installer. But the user would always want a clean system after uninstallatoin :)

So here you go with the approach to remove the installation directory via Direct Editor.

In the following example, I have a Basic MSI Project created using InstallShied 2012 Spring edition and assume that your application would create some files in the installed directory after installation, which would invalidate the removal of installation directory during uninstallation. The same solution applies to InstallScript MSI Project as well.

Take a look at the RemoveFiles table. You can remove specific files and files using wildcards. Once you remove those files, the folder should get removed as well on uninstall.
Something like the following should do the trick:
_MyFilesToRemove, <SomeComponentKey>, *.*, INSTALLDIR, 2

where <SomeComponentKey> is a key to an entry in the Component table. Any component will do, but if there is an .exe that actually creates the binary files, then perhpas you would want to use that .exe's component as you would only want the files to get removed when the corresponding .exe is removed.
Also, you may want to change *.* to *.<SomeSpecificExtension>

[Note: The above solution is basically an excerpt from MartinMarkevics's post in a community website.]