I would like to uninstall the "Realtek USB Ethernet Network Adapter" I can find it under System Information -> Software -> Installations in a list but don't know how to get rid of it.
Check the Realtek site for the latest driver of your USB Ethernet adapter and download it. The driver zip file should contain an uninstall.zip. Unzip this also and double-click the resulting uninstall.command file. Enter the admin (root) password and reboot your Mac.
Provided it's a RTL8153 chip you can also pour the following content into a uninstall.command file and execute it:
#!/bin/sh . /etc/rc.common echo " " echo "Please type the password of \"root\" to Uninstall ..." FROM=`dirname "$0"` echo "Removing Apple USB Ethernet Driver..." sudo kextunload /System/Library/Extensions/IONetworkingFamily.kext/Contents/PlugIns/AppleRTL815X*.kext sudo kextunload /Library/Extensions/AppleRTL815X*.kext sudo rm -rf /System/Library/Extensions/IONetworkingFamily.kext/Contents/PlugIns/AppleRTL815X*.kext sudo rm -rf /Library/Extensions/AppleRTL815X*.kext sudo touch /System/Library/Extensions/ sudo touch /Library/Extensions/ echo "Uninstall Complete."
Depending on your system version you may have to disable SIP.