This ‘feature’ has been annoying me for a while and after this has caused some confusion with some of my clients I decided to go and look where to disable this. Why this has been made a system wide default is beyond me.
Rather than in the users Calendar Settings this is actually in the Google Apps Admin Console (https://admin.google.com/)
Console –> Google Apps –> Settings for Calendar –> Sharing Settings
Disable the “Automatically add video calls to events created by a user” setting.