I hope you didn't install CleanMyMac as suggested in that article as CMM can do lots of hard to a system and apps. It's one of the apps that most of the experienced users in these forums consider akin to malware. I recommend you uninstall it according to the developer's instructions.
If you ever have to remove files that are listed as running and won't let you delete them boot into Safe Mode by booting with the Shift key held down and delete them from there. Then reboot normally.
NOTE: Safe Mode boot can take up to 10 minutes as it's doing the following;
• Verifies your startup disk and attempts to repair directory issues, if needed
• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)
• Prevents Startup Items and Login Items from opening automatically ⬅︎ ⬅︎ ⬅︎ ⬅︎
• Disables user-installed fonts
• Deletes font caches, kernel cache, and other system cache files
