How do I remove PC Tune Up on my computer

I have used PC Tune Up since 2007 and this year Dell and iolo are no longer in partnership and Dell PC Tune Up has changed to System Mechanics.  I downloaded it and then for some reason my computer went down and would not start.  Finally it started and restored back before I downloaded System Mechanics.  I have tried to download it but it keeps saying to remove the PC Tune Up Program and when I go to the control panel to do that it says that it can't uninstall because they can't find it.  Now System Mechanic won't install until I uninstall PC Tune Up.  How can I get PC TuneUp uninstalled???