You can try using AppDelete. It's free and will find and get rid of all associated application files that don't get deleted when you simply drag the application into the trash.
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Just be careful if you are looking to someday upgrade to a newer version of FC Studio. You will need to re-install FCP5 or at least keep your FCP system ID file, which is what FC looks for when installing an upgrade.(System Drive>Library>Application Support>ProApps)