wp_unschedule_event() │ WP 2.1.0

Unschedule a previously scheduled event.

The $timestamp and $hook parameters are required so that the event can be identified.

Used By: wp_clear_scheduled_hook()
Hooks from the function

Return

true|false|WP_Error. True if event successfully unscheduled. False or WP_Error on failure.

Usage

wp_unschedule_event( $timestamp, $hook, $args, $wp_error );
$timestamp(int) (required)
Unix timestamp (UTC) of the event.
$hook(string) (required)
Action hook of the event.
$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 boolean indicating success or failure, pre_unschedule_event filter added to short-circuit the function.
Since 5.7.0 The $wp_error parameter was added.

Code of wp_unschedule_event() WP 6.0

wp-includes/cron.php 
function wp_unschedule_event( $timestamp, $hook, $args = array(), $wp_error = false ) {
	// Make sure timestamp is a positive integer.
	if ( ! is_numeric( $timestamp ) || $timestamp <= 0 ) {
		if ( $wp_error ) {
			return new WP_Error(
				'invalid_timestamp',
				__( 'Event timestamp must be a valid Unix timestamp.' )
			);
		}

		return false;
	}

	/**
	 * Filter to preflight or hijack unscheduling of events.
	 *
	 * 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 true if the event was successfully
	 * unscheduled, false if not.
	 *
	 * @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|bool|WP_Error $pre       Value to return instead. Default null to continue unscheduling the event.
	 * @param int                $timestamp Timestamp for when to run 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_unschedule_event', null, $timestamp, $hook, $args, $wp_error );

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

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

		return $pre;
	}

	$crons = _get_cron_array();
	$key   = md5( serialize( $args ) );
	unset( $crons[ $timestamp ][ $hook ][ $key ] );
	if ( empty( $crons[ $timestamp ][ $hook ] ) ) {
		unset( $crons[ $timestamp ][ $hook ] );
	}
	if ( empty( $crons[ $timestamp ] ) ) {
		unset( $crons[ $timestamp ] );
	}

	return _set_cron_array( $crons, $wp_error );
}

cron (schedule)