Remove FCPX plug-in

Check 3 place:

Movies> Motion Templates>
/Library/Plug-ins/xxx/,
/Library/Application Support/Final Cut Pro/xxx

For audio plugin, check and clean this location, empty trash.

empty: "/Library/Audio/Plug-Ins/Components" and "~/Library/Audio/Plug-Ins/Components"

• Reset Final Cut Pro's plug-in cache
  In the Finder press and hold the Option key and choose Go > Library. (The Library option will only appear while holding the Option key)
• In the Finder window go into ~Library/Preferences/
• Move the com.apple.audio.InfoHelper.plist file to the Desktop.
• Restart the computer, then open Final Cut Pro X. All installed Audio Unit plug-ins will be rescanned.