How to get current page nearest parent id?

try this.

global $post;     // if outside the loop
$page_object = get_queried_object();
$page_id  = get_queried_object_id(); // Get current page id

$args = array(
    'sort_order' => 'ASC',
    'sort_column' => 'post_title',
    'hierarchical' => 1,
    'exclude' => '',
    'include' => $page_id,
    'meta_key' => '',
    'meta_value' => '',
    'authors' => '',
    'child_of' => 0,
    'parent' => -1,
    'exclude_tree' => '',
    'number' => '',
    'offset' => 0,
    'post_type' => 'page',
    'post_status' => 'publish'
); 
$pages = get_pages($args);

$parentID = $pages[0]->post_parent; // Get current page parent id

This will gives you current page parent id, not top-level id $parentID = $pages[0]->post_parent;