Over ride function in parent – can't find info…

Hey guys… I’ve been reading and i’m unsure from what i’m reading if i should be using the filter technique or add action technique, etc…

Basically the parent theme has a simple function called get_the_author…

In my child theme I want to override it and have it return blank.

It’s not registered via addAction, or addFilter, etc… it’s just a simple function. Example:

/**
* Retrieve the author of the current post.
* @uses $authordata The current author’s DB object.
* @uses apply_filters() Calls ‘the_author’ hook on the author display name.
*
* @param string $deprecated Deprecated.
* @return string The author’s display name.
*/
function get_the_author($deprecated = ”) {
global $authordata;

if ( !empty( $deprecated ) )
_deprecated_argument( __FUNCTION__, ‘2.1’ );
return apply_filters(‘the_author’, is_object($authordata) ? $authordata->display_name : null);
}

If a function is not registered… added via addAction, etc… can I still removeAction and addAction on it?