You should use the tool they provide for uninstall. The tool is available here:
http://www.bitdefender.com/files/KnowledgeBase/file/BitDefender_Uninst..._Tool.e for 32bit version
and
http://www.bitdefender.com/files/KnowledgeBase/file/BitDefender_Uninst..._Tool_x for 64bit version.
Also you can try to run another scan with CCleaner to make sure everything was uninstalled correctly.