Someone asked recently how to stop CCleaner 7 from starting with Windows, but there was no solution and topic is closed now. So in case anyone wants to do that:
Open Task Scheduler. In the library on the left choose Piriform folder, then select top task in the list on the right (CCleaner 7 - 1-S…) and disable it. The program will stop starting automatically and the icon will not be displayed on the taskbar. Hope that helps.