$ sudo launchctl unload /Library/LaunchDaemons/org.macosforge.xquartz.privileged_startx.plist
$ sudo rm -rf /opt/X11* /Library/Launch*/org.macosforge.xquartz.* /Applications/Utilities/XQuartz.app /etc/*paths.d/*XQuartz
$ sudo pkgutil --forget org.macosforge.xquartz.pkg