Remove WooThemes credit in Storefront footer

gistfile1.txt

add_action( 'init', 'custom_remove_footer_credit', 10 );

function custom_remove_footer_credit () {
    remove_action( 'storefront_footer', 'storefront_credit', 20 );
    add_action( 'storefront_footer', 'custom_storefront_credit', 20 );
} 

function custom_storefront_credit() {
	?>
	<div class="site-info">
		&copy; <?php echo get_bloginfo( 'name' ) . ' ' . get_the_date( 'Y' ); ?>
	</div><!-- .site-info -->
	<?php
}

Another person just wanting to say thank you!

You don't need to remove the action and add your own. There's a filter for this:

add_filter('storefront_credit_link', '__return_false');

This code works well. But one suggestion; some people might want to display the current year. The get_the_date retrieves the year of the blog. So, if you want to always display the most current year (to make your website look up-to-date), use "date" instead:
<?php echo get_bloginfo( 'name' ) . ' ' . date( 'Y' ); ?>