Uninstaller Info

You should use the official FileMaker Server Uninstaller to completely remove the previous version of FMS before installing a new one if you're not moving to new hardware at the same time.

The uninstaller is located at 'Macintosh HD > Library > FileMaker Server'

If you can't get into the FM server's console for some reason you can launch Terminal, there are several helpful commands to know

fmsadmin help commands

fmsadmin stop

fmsadmin res