you may find that they have been given root user permissions (higher than Admin - effectively "God") due to what they do, or because the programmer who wrote them wrote the installer incorrectly. I suggest you boot off your OSX CD and run Disk Utility, and run the permissions fixer on your drive before trying to remove them again. If that fails, you might use something like BatChmod to access the sudo (superuser do: root user) command to act as root temporarily, and then remove the files. You could also use sudo from the terminal, if you know how to.