I assume that you have also files in this folder that should be deleted. If there are no (arbitrary) subdirectories containing files it should be straight forward by using the RemoveFile
-table of the Windows Installer. As it will only delete the folder if it is empty, add an additional entry that will delete the files in it, e.g.:
<Directory Id="TARGETDIR" Name="SourceDir">
<Directory Id="ProgramFilesFolder">
<Directory Id="PACKAGE" Name="$(var.PkgFolder)">
<Component Id="PackagesFiles" Guid="$(var.FilesGUID)">
<RegistryValue Root="HKLM" Key="$(var.RegKey)" Name="PkgDir" Type="string" Value="[PACKAGE]" KeyPath="yes" />
<RemoveFile Id="RemovePACKAGEFolderFiles" Directory="PACKAGE" Name="*.*" On="both" />
<RemoveFolder Id="RemovePACKAGEFolder" Directory="PACKAGE" On="both" />
</Component>
</Directory>
</Directory>
</Directory>
This way you don't have to deal with any property setting. If you have other subdirectories with files you would have to repeat this also for these.
Another way would be to create a deferred custom action in the system context that will delete the folder completely, e.g. in VBScript.