Often, IT admins keep a copy in the deployment share or the "Support" folder of the original installation media.

: The tool will proceed to scrub the installation and will automatically prompt or perform a system restart to finalize the process. Troubleshooting Common Issues Re: How to Uninstall FortiClient 7.2.2 - Fortinet Community

FortiClient can be stubborn to uninstall using normal Windows methods. Fortinet provides a command-line removal tool named fcremove.exe that helps fully remove FortiClient and its services. This post explains what fcremove.exe does, when to use it, and provides clear, reproducible steps (including troubleshooting tips).

Upgrades or previous uninstall attempts failed midway, preventing any new instances from being installed.