CCleaner asks that when you delete registry entries. If the uninstaller is showing up in the list of registry fixes, then that probably means that the file doesn't exist anymore.
Start CCleaner and go to Tools. Is there anything in the program list about your game? If not, then just skip ahead to the next paragraph. If it is in the list, click on Run Uninstaller. If that doesn't work, click on Delete Entry and click on Yes. Then...
Just delete those game files you have (right-click and Delete) and run CCleaner again. Click on Run Cleaner and it will clear out your Temp folders and should get rid of any extra files that came with the game. Then if you want to clear your bad registry entries, click on Issues and Scan For Issues, then Fix Selected Issues. When CCleaner asks if you want to make a backup, click on Yes and pick a place to save the file. You'll need that if you decide that you want to undo the changes made.