Trashes or deletes a post or page.

When the post and page is permanently deleted, everything that is tied to
it is deleted also. This includes comments, post meta fields, and terms
associated with the post.

The post or page is moved to Trash instead of permanently deleted unless
Trash is disabled, item is already in the Trash, or $force_delete is true.

function wp_delete_post( $postid = 0, $force_delete = false ) {
	global $wpdb;

	$post = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM $wpdb->posts WHERE ID = %d", $postid ) );

	if ( ! $post ) {
		return $post;
	}

	$post = get_post( $post );

	if ( ! $force_delete && ( 'post' === $post->post_type || 'page' === $post->post_type ) && 'trash' !== get_post_status( $postid ) && EMPTY_TRASH_DAYS ) {
		return wp_trash_post( $postid );
	}

	if ( 'attachment' === $post->post_type ) {
		return wp_delete_attachment( $postid, $force_delete );
	}

	/**
	 * Filters whether a post deletion should take place.
	 *
	 * @since 4.4.0
	 *
	 * @param WP_Post|false|null $delete       Whether to go forward with deletion.
	 * @param WP_Post            $post         Post object.
	 * @param bool               $force_delete Whether to bypass the Trash.
	 */
	$check = apply_filters( 'pre_delete_post', null, $post, $force_delete );
	if ( null !== $check ) {
		return $check;
	}

	/**
	 * Fires before a post is deleted, at the start of wp_delete_post().
	 *
	 * @since 3.2.0
	 * @since 5.5.0 Added the `$post` parameter.
	 *
	 * @see wp_delete_post()
	 *
	 * @param int     $postid Post ID.
	 * @param WP_Post $post   Post object.
	 */
	do_action( 'before_delete_post', $postid, $post );

	delete_post_meta( $postid, '_wp_trash_meta_status' );
	delete_post_meta( $postid, '_wp_trash_meta_time' );

	wp_delete_object_term_relationships( $postid, get_object_taxonomies( $post->post_type ) );

	$parent_data  = array( 'post_parent' => $post->post_parent );
	$parent_where = array( 'post_parent' => $postid );

	if ( is_post_type_hierarchical( $post->post_type ) ) {
		// Point children of this page to its parent, also clean the cache of affected children.
		$children_query = $wpdb->prepare( "SELECT * FROM $wpdb->posts WHERE post_parent = %d AND post_type = %s", $postid, $post->post_type );
		$children       = $wpdb->get_results( $children_query );
		if ( $children ) {
			$wpdb->update( $wpdb->posts, $parent_data, $parent_where + array( 'post_type' => $post->post_type ) );
		}
	}

	// Do raw query. wp_get_post_revisions() is filtered.
	$revision_ids = $wpdb->get_col( $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE post_parent = %d AND post_type = 'revision'", $postid ) );
	// Use wp_delete_post (via wp_delete_post_revision) again. Ensures any meta/misplaced data gets cleaned up.
	foreach ( $revision_ids as $revision_id ) {
		wp_delete_post_revision( $revision_id );
	}

	// Point all attachments to this post up one level.
	$wpdb->update( $wpdb->posts, $parent_data, $parent_where + array( 'post_type' => 'attachment' ) );

	wp_defer_comment_counting( true );

	$comment_ids = $wpdb->get_col( $wpdb->prepare( "SELECT comment_ID FROM $wpdb->comments WHERE comment_post_ID = %d ORDER BY comment_ID DESC", $postid ) );
	foreach ( $comment_ids as $comment_id ) {
		wp_delete_comment( $comment_id, true );
	}

	wp_defer_comment_counting( false );

	$post_meta_ids = $wpdb->get_col( $wpdb->prepare( "SELECT meta_id FROM $wpdb->postmeta WHERE post_id = %d ", $postid ) );
	foreach ( $post_meta_ids as $mid ) {
		delete_metadata_by_mid( 'post', $mid );
	}

	/**
	 * Fires immediately before a post is deleted from the database.
	 *
	 * @since 1.2.0
	 * @since 5.5.0 Added the `$post` parameter.
	 *
	 * @param int     $postid Post ID.
	 * @param WP_Post $post   Post object.
	 */
	do_action( 'delete_post', $postid, $post );

	$result = $wpdb->delete( $wpdb->posts, array( 'ID' => $postid ) );
	if ( ! $result ) {
		return false;
	}

	/**
	 * Fires immediately after a post is deleted from the database.
	 *
	 * @since 2.2.0
	 * @since 5.5.0 Added the `$post` parameter.
	 *
	 * @param int     $postid Post ID.
	 * @param WP_Post $post   Post object.
	 */
	do_action( 'deleted_post', $postid, $post );

	clean_post_cache( $post );

	if ( is_post_type_hierarchical( $post->post_type ) && $children ) {
		foreach ( $children as $child ) {
			clean_post_cache( $child );
		}
	}

	wp_clear_scheduled_hook( 'publish_future_post', array( $postid ) );

	/**
	 * Fires after a post is deleted, at the conclusion of wp_delete_post().
	 *
	 * @since 3.2.0
	 * @since 5.5.0 Added the `$post` parameter.
	 *
	 * @see wp_delete_post()
	 *
	 * @param int     $postid Post ID.
	 * @param WP_Post $post   Post object.
	 */
	do_action( 'after_delete_post', $postid, $post );

	return $post;
}