To disable the SysMain (Superfetch) service and resolve high CPU usage, you can choose one of the following methods: Open the Services utility and find the SysMain service, stop the service and set the startup type to Disabled, or access the Registry Editor and navigate to the appropriate key to modify the value of the SysMain service to disable it, or use the Command Prompt as an administrator and enter the command 'net.exe stop superfetch' to stop the service.