- You do not need CleanMyMac. Uninstall it.
- You don't need MalwareBytes unless you believe you have malware. Uninstall it
- You don't need maintenance software. Uninstall it.
You do not need to pay for and install this kind of software because it is included as part of macOS. macOS runs automated cleanup routines on a regular schedule. macOS has built-in anti-malware software that is regularly updated as needed if you have Automatic Updates enabled in Software Update preferences pane.
Never install any software on your computer until you have learned how to remove it. Never install any software on your computer unless you know what it does and that you need it. Never alter, delete, or remove files and/or folders not located in your Home folder.
Before You Upgrade macOS
- Fix any problems before upgrading.
- Run First Aid in Disk Utility while booted from your Recovery HD.
- Backup. Make a bootable clone using CarbonCopy Cloner or use TimeMachine.
- Be sure your startup disk has 18-20GB of free space during the installation.
- Upgrade third-party software for compatibility. See App Compatibility Table - RoaringApps. If you have mission critical software, then DO NOT upgrade until you know that software is compatible with the version of macOS you are about to install.
- Disconnect all third-party peripherals.
- Download the installer which will be in the Applications folder. Quit the installer after it opens, then make a copy of the installer and save it in the Downloads folder. The one in the Applications folder will be deleted after a successful installation.
- The download is large, anywhere between 5 and 9GBs. It takes time to complete. Be patient.
- Double-click on the installer in the Applications folder. Click on the start button to begin the installation.