Turn off “This is the Primary Sidebar Widget Area” message

This code handles the sidebar:

add_action( 'genesis_sidebar', 'genesis_do_sidebar' );
/**
 * Echo primary sidebar default content.
 *
 * Only shows if sidebar is empty, and current user has the ability to edit theme options (manage widgets).
 *
 * @since 1.2.0
 */
function genesis_do_sidebar() {

    if ( ! dynamic_sidebar( 'sidebar' ) && current_user_can( 'edit_theme_options' )  ) {
        genesis_default_widget_area_content( __( 'Primary Sidebar Widget Area', 'genesis' ) );
    }

}

You can unhook genesis_do_sidebar from genesis_sidebar, then wire up your own sidebar function to prevent the default content from being output:

remove_action( 'genesis_sidebar', 'genesis_do_sidebar' );
add_action( 'genesis_sidebar', 'wpse_genesis_do_sidebar' );
/**
 * Outputs widgets for sidebar without default content.
 */
function wpse_genesis_do_sidebar() {
    dynamic_sidebar( 'sidebar' );
}