A clean boot is nothing more than preventing everything from running at StartUp so go from Start to Run and type msconfig into the Open box then hit the Enter key.
Click on the StartUp tab and untick everything then click Apply. Click the Services tab and then on "Hide all Microsoft" then look at what's left - anything you don't really need, untick and that disables iot completely so if you want it back afterwards, you need to reset it in Services.
Click Apply again and OK your way out then after the restart, tick "Don't show this message again" and hit Enter. You're now clean booted so now press Control, Shift and Escape together to see the Task Manager, click on the Processes tab to see what's still running.