GroupContactTable::deleteByGroupId

static function deleteByGroupId($groupId)
{
	$items = static::getList([
		'select' => ['ID', 'GROUP_ID', 'TYPE_ID'],
		'filter' => ['=GROUP_ID' => $groupId]
	]);
	foreach ($items as $primary)
	{
		$result = static::delete($primary);
		if (!$result->isSuccess())
		{
			return false;
		}
	}

	return true;
}