disable upstart job

[Tom Jones]

This is a really basic sysadmin operation, but documentation seems
to be lacking and / or software buggy.

The question is how, in general, does one disable an upstart job?

Creating /etc/init/network-manager.override with "manual" in it
doesn't work.  Removing /etc/init/network-manager altogether does
work.  Is this expected, and if so based on what documentation /
interface specification?

This is Ubuntu 14.10.

Please don't reply with "upstart is about to be replaced with foo",
I'm trying to find out the best way to configure the system I have
running here.

  Tom.

[1] <http://askubuntu.com/questions/19320/how-to-enable-or-disable-services>