Occasionally installing an app that adds virtual audio or camera like the Evernote video application mmhmm, you are left with residuals in your system that can make your life difficult when using applications where it is not possible to select the primary or default device.
There are two key spots in macOS where those plugins are installed before there's what I have done for removing mmhmm virtual devices. I was part of their beta program and when I deleted the beta binary I was having all kinds of nightmares with Google Chat. That problem is now gone and I am sharing how I did it.
Open your terminal window (I am still on Bash)
First, you want to stop the associated daemon to the app you are removing. You can find the list of all you have in your system by using this command sudo launchctl list
launchctl stop com.all-turtles.mmhmm.Camera.Assistant
launchctl unload /Library/LaunchAgents/com.all-turtles.mmhmm.Camera.Assistant.plist
Now that is delectable because is no longer in memory, you can use the remove command
You do the same for the virtual audio
rm -rf /Library/CoreMediaIO/Plug-Ins/DAL/mmhmmCamera.plugin
rm -rf /Library/Audio/Plug-Ins/HAL/mmhmmAudio.driver
Finally, you make sure that the system manager is aware to recount all devices so that all (closed) apps next time will have the correct count of the devices available. This is to avoid a reboot :=)
launchctl kickstart -kp system/com.apple.audio.coreaudiod
It took me some trial error but ultimately it worked like a charm.
Happy restoring, of your sanity, included!