System Cleanup is a “system optimizer” that uses false positives to convince users that their systems have problems. Malwarebytes can detect and remove this potentially unwanted application. The full version of Malwarebyte would have protected you against the installer. It would have warned you before the application could install itself, giving you a chance to stop it before it became too late. We hope our application and this guide have helped you eradicate this system optimizer. We block access to their domain.”]
Source: https://forums.malwarebytes.com/topic/199513-removal-instructions-for-system-cleanup/