You can turn off the wireless Internet connection on your iMac through the Wireless menu that is always on the top of your screen, but the option to turn off your Ethernet connection isn’t quite as prominent. While unplugging the Ethernet cord technically works, there is also a software-based method for turning off the Internet through your Ethernet port. The Network section of your iMac’s System Preferences has a list of all your computer’s network connections and the interface for deactivating them. Tips Writer Bio
