cPanel has a 'Feature Manager' in WHM that allows you to disable PHP Selector for some of the packages that you offer.
In reality it only disables the icon in cPanel interface. Yet, in most cases it should be enough in shared hosting settings.
You can find more info on 'Feature Manager' here: http://docs.cpanel.net/twiki/bin/view/11_30/WHMDocs/FeatureManager
Once PHP Selector is enabled, you can find it in the Feature Manager. Disabling it in Feature Manager, will remove the icon for users that are using that particular 'Feature List'