delete_transient

 *
 * @since 1.2.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $option Name of the option to delete. Expected to not be SQL-escaped.
 * @return bool True if the option was deleted, false otherwise.
 */
function delete_option( $option ) {
	global $wpdb;

	$option = trim( $option );
	if ( empty( $option ) ) {
		return false;
	}

	wp_protect_special_option( $option );

	// Get the ID, if no ID then return.
	$row = $wpdb->get_row( $wpdb->prepare( "SELECT autoload FROM $wpdb->options WHERE option_name = %s", $option ) );
	if ( is_null( $row ) ) {
		return false;
	}

	/**
	 * Fires immediately before an option is deleted.
	 *
	 * @since 2.9.0
	 *
	 * @param string $option Name of the option to delete.
	 */
	do_action( 'delete_option', $option );

	$result = $wpdb->delete( $wpdb->options, array( 'option_name' => $option ) );

	if ( ! wp_installing() ) {
		if ( 'yes' === $row->autoload ) {
			$alloptions = wp_load_alloptions( true );