wp_clear_scheduled_hook() │ WP 2.1.0

Unschedules all events attached to the hook with the specified arguments.

Warning: This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE. For information about casting to booleans see the PHP documentation. Use the === operator for testing the return value of this function.

Uses: wp_unschedule_event()
Hooks from the function

Return

Int|false|WP_Error. On success an integer indicating number of events unscheduled (0 indicates no events were registered with the hook and arguments combination), false or WP_Error if unscheduling one or more events fail.

Usage

wp_clear_scheduled_hook( $hook, $args, $wp_error );
$hook(string) (required)
Action hook, the execution of which will be unscheduled.
$args(array)
Array containing each separate argument to pass to the hook's callback function. Although not passed to a callback, these arguments are used to uniquely identify the event, so they should be the same as those used when originally scheduling the event.
Default: empty array
$wp_error(true|false)
Whether to return a WP_Error on failure.
Default: false

Changelog

Since 2.1.0 Introduced.
Since 5.1.0 Return value modified to indicate success or failure, pre_clear_scheduled_hook filter added to short-circuit the function.
Since 5.7.0 The $wp_error parameter was added.

Code of wp_clear_scheduled_hook() WP 5.9.3

wp-includes/cron.php 
function wp_clear_scheduled_hook( $hook, $args = array(), $wp_error = false ) {
	// Backward compatibility.
	// Previously, this function took the arguments as discrete vars rather than an array like the rest of the API.
	if ( ! is_array( $args ) ) {
		_deprecated_argument( __FUNCTION__, '3.0.0', __( 'This argument has changed to an array to match the behavior of the other cron functions.' ) );
		$args     = array_slice( func_get_args(), 1 ); // phpcs:ignore PHPCompatibility.FunctionUse.ArgumentFunctionsReportCurrentValue.NeedsInspection
		$wp_error = false;
	}

	/**
	 * Filter to preflight or hijack clearing a scheduled hook.
	 *
	 * Returning a non-null value will short-circuit the normal unscheduling
	 * process, causing the function to return the filtered value instead.
	 *
	 * For plugins replacing wp-cron, return the number of events successfully
	 * unscheduled (zero if no events were registered with the hook) or false
	 * if unscheduling one or more events fails.
	 *
	 * @since 5.1.0
	 * @since 5.7.0 The `$wp_error` parameter was added, and a `WP_Error` object can now be returned.
	 *
	 * @param null|int|false|WP_Error $pre      Value to return instead. Default null to continue unscheduling the event.
	 * @param string                  $hook     Action hook, the execution of which will be unscheduled.
	 * @param array                   $args     Arguments to pass to the hook's callback function.
	 * @param bool                    $wp_error Whether to return a WP_Error on failure.
	 */
	$pre = apply_filters( 'pre_clear_scheduled_hook', null, $hook, $args, $wp_error );

	if ( null !== $pre ) {
		if ( $wp_error && false === $pre ) {
			return new WP_Error(
				'pre_clear_scheduled_hook_false',
				__( 'A plugin prevented the hook from being cleared.' )
			);
		}

		if ( ! $wp_error && is_wp_error( $pre ) ) {
			return false;
		}

		return $pre;
	}

	/*
	 * This logic duplicates wp_next_scheduled().
	 * It's required due to a scenario where wp_unschedule_event() fails due to update_option() failing,
	 * and, wp_next_scheduled() returns the same schedule in an infinite loop.
	 */
	$crons = _get_cron_array();
	if ( empty( $crons ) ) {
		return 0;
	}

	$results = array();
	$key     = md5( serialize( $args ) );

	foreach ( $crons as $timestamp => $cron ) {
		if ( isset( $cron[ $hook ][ $key ] ) ) {
			$results[] = wp_unschedule_event( $timestamp, $hook, $args, true );
		}
	}

	$errors = array_filter( $results, 'is_wp_error' );
	$error  = new WP_Error();

	if ( $errors ) {
		if ( $wp_error ) {
			array_walk( $errors, array( $error, 'merge_from' ) );

			return $error;
		}

		return false;
	}

	return count( $results );
}

cron (schedule)