I'd be looking at Win32API::File's use of CreateFile and the FILE_FLAG_DELETE_ON_CLOSE flag. If your plain unlink doesn't work because the file is opened exclusively for PowerPoint, you can try opening it with this other flag. This flag is then set on the open handle so whenever PowerPoint exits, the file gets deleted. That's the basic idea I've gathered from other people who have dealt with this sort of problem on Windows.