Uninstalling a NoMachine server DEB package with: 

$ sudo dpkg -r  nomachine

or:

$ sudo dpkg -P  nomachine

or:

$ sudo apt -q purge -y nomachine

leaves this symlink on the system:

/etc/systemd/system/multi-user.target.wants/nxserver.service -> /lib/systemd/system/nxserver.service

 This symlink is created during the installation of NoMachine and must be deleted when the package is uninstalled.