use Bitrix\Highloadblock as HL;
$filter = array(
'select' => array('ID'),
'filter' => array('=NAME' => "CODE_OF_YOUR_HLBLOCK")
);
$hlblock = HL\HighloadBlockTable::getList($filter)->fetch();
if(is_array($hlblock) && !empty($hlblock))
{
HL\HighloadBlockTable::delete($hlblock['ID']);
}