Uninstalling NoMachine should remove all audio drivers used by this software. In some cases it has been noticed that 'NoMachine Audio Adapter' and 'NoMachine Microphone Adapter' are still listed in the menu of applications like Facetime.

Try to close and reopen the application and verify if NoMachine Adapters are still listed in the menu.

If they are still present, restart manually the Core Audio system by executing in a Terminal:

sudo killall coreaudiod

If also this doesn't help, check if NoMachine audio drivers are still present on the system by running in a Terminal:

ls /Library/Audio/Plug-Ins/HAL/.| grep NM  

When drivers are present, output is:
ls /Library/Audio/Plug-Ins/HAL/.| grep NM
NMAudio.driver
NMAudioMic.driver

To manually remove drivers and make changes effective on the system:

1) run in a terminal:

sudo rm -rf NMAudio.driver NMAudioMic.driver

2) then restart the Core Audio system:

sudo killall coreaudiod