Ocultar todos los avisos de actualizaciones

remove_core_updates.php

<?php

/*
 * Hide all updates
 */
function remove_core_updates(){
	global $wp_version;
	return(object) array(
		'last_checked'=> time(), 
		'version_checked'=> $wp_version
	);
}
add_filter('pre_site_transient_update_core','remove_core_updates');
add_filter('pre_site_transient_update_plugins','remove_core_updates');
add_filter('pre_site_transient_update_themes','remove_core_updates');