Uninstall of FortiClient 6.2.0.0128 on my private Windows 10 PC is not working

Uninstall of FortiClient on my private Windows 10 PC is not working.

I get the message "Windows cannot access the specified device, path or file. You may not have the appropriate permissions to access the item" 

I manually stop the FortiClient service in the system tray before uninstalling. Btw, where is the option to avoid automatically running this at each startup?

I updated FortiClient to the latest version, no luck.

I rebooted and retried a few times, no luck.