Disabling the FortiClient VPN from starting automatically during user login is not currently possible from System Preferences > Users & Groups > Login Items like in most cases.
Instead, FortiClient uses LaunchAgents to start itself – what we have to do is edit the following plist files with our text editor of choice.
1. Open the following plist file using elevated privileges and edit it with nano using the Terminal:
sudo nano /Library/LaunchAgents/com.fortinet.forticlient.credential_store.plist
2. Find the RunAtLoad key and change true to false:
3. Save and exit nano by pressing [CTRL + X] , [Y] and [Return/Enter]
4. Do the same steps for fct_launcher as well:
sudo nano /Library/LaunchAgents/com.fortinet.forticlient.fct_launcher.plist
5. Change RunAtLoad to false: