Thank you so much! Got on my nerves since ages! ReportCrash ran with 200%+ on my Activity Monitor all the time, although CCleaner did not run! On the console, this error was repeated in a loop:
com.apple.xpc.launchd[1] (com.piriform.ccleaner.CCleanerAgent): Service only ran for 0 seconds. Pushing respawn out by 1 seconds.
I deleted it this way (you will need root access, this is why I used sudo):
cd /Library/PrivilegedHelperTools
sudo rm com.piriform.ccleaner.CCleanerAgent