Once a device is discovered, the only way to delete it is to disconnect it from the network (see "Deleting Devices"). If the device is plugged back in, it will be re-discovered.
To disable automatic device discovery
1.Open Main Menu –> System Administration (shortcut Ctrl+Alt+A) –> General tab
2.Uncheck Enable devices and servers auto discovery in the System Settings section
3.When finished, press OK to apply or Cancel to discard changes
IMPORTANT: Once auto-discovery is disabled, new devices and servers will no longer be auto-discovered, they will have to be added manually.