Do you have any other cleaner or RAM booster app installed?It is not Clean Master. I do not have this app. However I install it and uninstall it. but the Icon still appearing.
Does it ever give a notification in the pull down notifications? If so you can tap on the down carat or 3 dots to see what app it is from.
Have you tried looking in system apps? If it is there the virus cannot be wiped unless you flash a clean rom. The Samsung guy at Best Buy can do it in a Samsung phone.Sadly it doesn't.