LibreOffice error: "Either another instance of LibreOffice is accessing your personal settings or your personal settings are locked"

According to the LibreOffice docs and this similar Ask Ubuntu Q&A, it stores a .lock file ~/Library/Application Support/libreoffice/4/user on OS X to indicate a session is active and running.

To clean it up:

1. Make sure no instances of LibreOffice are currently running.
2. Open the Terminal application
3. Optional: Check to see if lock file exists, at the prompt type: ls -l ~/Library/Application\ Support/LibreOffice/?/user/.lock
   If you see "cannot access" this means the lock file is not present.
4. At the prompt type: rm -f ~/Library/Application\ Support/LibreOffice/?/user/.lock
5. Close the Terminal application
6. Start LibreOffice

There are several lock files which may require deletion:

rm -rf ~/Library/Application\ Support/LibreOffice/*/user/.lock
rm -rf ~/Library/Application\ Support/LibreOffice/*/.lock

P.S.: This fix applies to OS X 10.9 and LibreOffice 4.2; Actual results may vary.