To uninstall True-Fi, go to True-Fi settings (or use the Mac native drop-down menu bar) then click on the 'Uninstall' button at the bottom of True-Fi settings screen:
If you still have True-Fi listed as an available output device after uninstalling (or if you've removed the True-Fi manually, not using the 'Uninstall' button), you'll need to enter a couple of commands in the Terminal app to remove True-Fi completely. Launch the Terminal app and copy-paste both of the following commands into the Terminal window. Hit 'Enter' to execute each command:
MacOS 10.14 Mojave and lower: sudo kextunload /System/Library/Extensions/TrueFi.kext
sudo rm -r /System/Library/Extensions/TrueFi.kext
MacOS 10.15 Catalina: sudo kextunload /Library/Extensions/TrueFi.kext
sudo rm -r /Library/Extensions/TrueFi.kext
If True-Fi audio device is still present on your Mac after completing these instructions, please contact the support team here and we'll have a closer look at the problem.