After I had bought the Fantastical calendar app for my Mac, I had some annoying problems with the parallel running build in the calendar which I used before. Every every message, reminder, etc. appeared twice!
First, I tried to stop the running build in calendar app process with the Activity Monitor, but it didn’t work. I remembered to a similar problem I previously had, and I was using the launch daemon to unload the running app.
I was checking the LaunchAgents folder, found the calendar app and could stop the process by using the command:
launchctl unload -w /System/Library/LaunchAgents/com.apple.CalendarAgent.plist