How to stop the Forticlient Scheduler

Last Friday I installed Forticlient SSL VPN in order to connect to one of my client's pc remotely. I immediately noticed that Forticlient VPN disconnected automatically all of my other active VPNs, but at the time thought nothing of it.
Today I wanted to connect with my OpenVPN account, but could not do it because the Forticlient VPN and Forticlient Scheduler services were configured to start at Windows boot: I opened the Windows Services utility and tried to set the startup type of both processes to "Manual", but the FortiClient Scheduler kept giving me the error: Parameter is incorrect
After much searching on internet for solutions, I found out that FortiClient Scheduler is used by an active service called FortiShield, and that's why I could neither stop nor disable the process even with administrator rights; so I opened a window console and typed this:

After this I could stop the FortiClient Scheduler and set its startup type to "Manual". I hope this post will help others with the same problem!