Please note that CCleaner can no longer "Erase Free Space" in OS X 10.11 (El Capitan) and Apple has disabled the feature within Disk Utility. There is apparently another advanced option to do this via command line in Terminal although for the average user the feature cannot be implemented. When currently running Erase Free Space in CCleaner it will stop or freeze after a few seconds and CCleaner has to be closed out. Question:
Will "Erase Free Space" need to be removed from CCleaner?
Additional info here:
http://www.macissues.com/2015/10/03/how-to-securely-delete-files-in-os-x-10-11-el-capitan/
Also found some outdated info in this link:
https://support.apple.com/kb/PH22192?locale=en_US
There is no more "Secure Empty Trash"