Open Task Manager and EndTask any running CCleaner processes, then try the uninstall again. If that doesn't help perhaps uninstalling it by a different more robust means will work with either of the two freeware uninstallers linked below.
Seriously, WTF is this? A more robust means????? No. You uninstall things by clicking uninstall. Only s***ty virus crapware you need to uninstall by more robust means.