Marcelo Pedra on "[Plugin: Wordfence Security] Remove WF from Database"

@RobinInTexas
@Michael Wiener
If possible, the BEST option is to get rid of unneeded plugins, which ultimately will add memory usage to your WP installation. So, if you have a control panel for your hosting, try using phpmyadmin, which is able to force delete those leftovers.
If such a tool is unavailable for any reason and wp-optimize usage is the only way out, remember to deactivate these cleaning plugins after use, to alleviate the performance of your entire WordPress installation. In brief: activate it, use it, deactivate it till next time. :)