remove_action returns FALSE

I’m trying to remove the canonical link reference from my page headers and I’m using the following code in my functions.php:

remove_action('wp_head', 'rel_canonical');

However, when I test the return value of remove_action it’s value is FALSE and I notice that the canonical link reference is still rendered in the head of my pages.

I’ve tried wrapping the remove_action in an init but I get the same result:

function my_init()
{
   remove_action('wp_head', 'rel_canonical');
}

add_action('init', 'my_init');

How do I remove the canonical link reference from my page headers?