CCleaner searches for and removes private information that can be used to track your computer usage. CCLeaner searches for and removes problem entries in the Windows registry. CCleaner can uninstall programs you can’t uninstall from the control panel, remove startup items to speed up system boot times, delete old restore points, and securely wipe files from your computer making it impossible to recover them.
See the article here: CCleaner – Clean Registry and Personal Information [Tutorial]