The running processes, ndtrack and ndschedag, are not actually services. They are short lived programs (agents if you like) which are launched by the long running ndtask service based on a schedule. The ndtask service maintains a schedule and at the appointed times will execute the ndschedag agent. The ndschedag agent will determine what actually needs to be done at the scheduled time, and in this case, will launch the ndtrack agent. So the process tree will be ndtask -> ndschedag -> ndtrack.
If you stop the ndtask service, you will find ndschedag and ndtrack can continue executing until ndtrack completes its inventory gathering task, at which point ndtrack, and its parent ndschedag, will exit naturally. If for some reason you need to terminate ndtrack before it completes its inventory gathering, then you will need to use the normal process termination commands for the operating system (e.g. kill).