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.

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.