Remove path from the create/edit a post view

Use the filter tiny_mce_before_init to customise the default configuration;

function wpse_11867_tiny_mce( $config ) {
    $config['theme_advanced_path'] = false;
    return $config;
}

add_filter( 'tiny_mce_before_init', 'wpse_11867_tiny_mce' );

Check out all the options available on the Tiny MCE documentation.