Old Libraries won't go away!

Hi Folks:

I often use "CLT click" or "RT click" on the FCP icon in the dock to launch one of my recent FCP Libraries. For some reason, old Libraries that I have finished and completely deleted from my computer and from my drives will still show up as choices to open in FCP. If I try to "open" them nothing happens - FCP doesn't even launch (I assume because they don't exist). However, they still show up in the "recents" list on the dock. I can't for the life of me find a way to get rid of these "ghosts" from the past. I've tried trashing prefs. I've tried clearing recents in the Open Menu, I've even tried to "toss" them from the dock like you do to get rid of program icons you no longer need there. All to no avail. Does anyone know how to clear these not so "recents" from the dock once and for all. I'm afraid to imagine the list of "ghosts" that might still be there after a year of work.

I'm running FCPX 10.2.3 - with OS X El Capitan 10.11.6 - on a 2015 21.5 inch iMac - 2.8 GHz Intal Core i5 - 8 GB ram - Intel Iris Pro 6200 1536 MB

Would appreciate any help or ideas.

Norm