The reason why `rm -f "~/Library/Application Support/LibreOffice/*/user/.lock"` does ***not*** work is because system Terminal has a special way of recognizing spaces (Application Support). Additionally, I believe that the "-f" parameter should be a "-rf" The actual command will be: 

    rm -rf "~/Library/Application\ Support/LibreOffice/*/user/.lock"
But wait! There is also another ".lock" file that should be deleted:

    rm -rf "~/Library/Application\ Support/LibreOffice/4/.lock"
If the error still occurs, execute the following:

    rm -rf "~/Library/Application\ Support/LibreOffice/4/user/.lock"
The error should be fixed by now.

 Notice the backwards slash in between Application and Support!
P.S.: This fix applies to OS X 10.9 and LibreOffice 4.2; Actual results may vary.