function mysite_page_metabox() {
    add_meta_box(
        'remove-title',
        __('Hide Page Title', 'textdomain' ),
        'hide_title_callback',
        'page',
        'side',
        'high'
    );
}
add_action( 'add_meta_boxes' , 'mysite_page_metabox');

function hide_title_callback() {
    $value = get_post_meta(get_the_ID(), '_mysite_meta_hide_title', true);
    ?>
    <?php if($value == "on") : ?>
        <label for="hide">Hide: </label><input type="checkbox" name="hide" checked>
    <?php else : ?>
        <label for="hide">Hide: </label><input type="checkbox" name="hide">
    <?php endif; ?>
    <?php
}


// Save meta key and value
function mysite_save_postdata($post_id)
{
    if ( isset( $_POST['hide']) ) {
        update_post_meta(
            $post_id,
            '_mysite_meta_hide_title',
            sanitize_text_field( $_POST['hide'] )
        );
    } else {
        update_post_meta(
            $post_id,
            '_mysite_meta_hide_title',
            sanitize_text_field( "off" )
        );
    }
}
add_action('save_post', 'mysite_save_postdata');

<!--Start the hide title-->
    <?php
        $hide_title_status = get_post_meta( get_the_ID(), '_mysite_meta_hide_title', true);
        $post_id = get_the_ID();
        if($hide_title_status == "off" || !metadata_exists( 'post', $post_id, '_mysite_meta_hide_title' ) ) :
    ?>
        <header class="entry-header">
            <?php the_title( '<h1 class="entry-title">', '</h1>' ); ?>
        </header><!-- .entry-header -->
    <?php endif; ?> <!--End the hide title-->