WordPress at a glance
function is not described

_reset_front_page_settings_for_post() WP 3.7.0

Reset the page_on_front, show_on_front, and page_for_post settings when a linked page is deleted or trashed.

Also ensures the post is no longer sticky.

No Hooks.

Return

Nothing (null).

Usage

_reset_front_page_settings_for_post( $post_id );
$post_id(int) (required)
Post ID.

Code of reset front page settings for post: wp-includes/post.php WP 5.2.2

<?php
function _reset_front_page_settings_for_post( $post_id ) {
	$post = get_post( $post_id );
	if ( 'page' == $post->post_type ) {
		/*
		  * If the page is defined in option page_on_front or post_for_posts,
		  * adjust the corresponding options.
		  */
		if ( get_option( 'page_on_front' ) == $post->ID ) {
			update_option( 'show_on_front', 'posts' );
			update_option( 'page_on_front', 0 );
		}
		if ( get_option( 'page_for_posts' ) == $post->ID ) {
			delete_option( 'page_for_posts', 0 );
		}
	}
	unstick_post( $post->ID );
}