Is there a way to disable Facetime from starting?

Solution 1:

Navigate to: System Preferences -> Users & Groups -> Login Items.

On this screen you can choose which programs will open automatically upon startup. You can remove FaceTime from this list to disable it opening on startup.

You can also add any programs you would actually like to start when you boot up.

Solution 2:

I found this way to keep Facetime from running at startup. Since it's a rather insidious program, you have to take much more drastic steps to force this program to play nicely.

There is a .plist file that can cause Facetime to run during startup. Delete that file, and it should no longer start automatically. It should still run normally if you want (by clicking on the app icon in the Applications folder).

The file can be found at:

/Users/[account_name]/Library/Preferences/com.apple.facetime.plist

...where [account_name] is your user name. The easiest way to find it is through terminal as the Library/ directory is usually hidden in the graphical interfaces (Finder).

Just delete that file and reboot. I'm pretty sure nothing important is stored in that file, other than "run me during startup!"

Tested on High Sierra.