How to delete the Article info (Joomla 3.0)?

As the title of question, I want delete all info in a Joomla article (ex :author, create date, print icon, ...) .When I create an article, it will show default . I try to hide it, but it only hide and Joomla still create the empty tag of info . Here, you can see :

Please avoid to customize the core Joomla files like article or other.If You want to change or customize the article default file (like you say the article info) by using the template overridden method.for more details go the link below:

How to override the output from the Joomla! core