WP-Mix

If for whatever reason you would like to disable WordPress update reminders, read on.

By default, WordPress displays “reminder” messages across all pages in the Admin area whenever updates are available. It’s recommended that you leave this feature enabled, but it’s possible to disable whenever it makes sense to do so. Just add the following code to your functions.php file:

# WP versions 2.3 to 2.7:
add_action( 'admin_menu', create_function( '$a', "remove_action( 'load-plugins.php', 'wp_update_plugins' );") );
add_action( 'admin_init', create_function( '$a', "remove_action( 'admin_init', 'wp_update_plugins' );"), 2 );
add_action( 'init', create_function( '$a', "remove_action( 'init', 'wp_update_plugins' );"), 2 );
add_filter( 'pre_option_update_plugins', create_function( '$a', "return null;" ) );

# WP versions 2.8 to 3.0:
remove_action( 'load-plugins.php', 'wp_update_plugins' );
remove_action( 'load-update.php', 'wp_update_plugins' );
remove_action( 'admin_init', '_maybe_update_plugins' );
remove_action( 'wp_update_plugins', 'wp_update_plugins' );
add_filter( 'pre_transient_update_plugins', create_function( '$a', "return null;" ) );

# WP versions 3.0 and better:
remove_action( 'load-update-core.php', 'wp_update_plugins' );
add_filter( 'pre_site_transient_update_plugins', create_function( '$a', "return null;" ) );

Feel free to remove or comment-out code for any unused versions of WordPress.