CTaskLog::DeleteByTaskId

static function DeleteByTaskId($in_taskId)
{
	$taskId = (int)$in_taskId;

	if ((!is_numeric($in_taskId)) || ($taskId < 1))
		throw new Exception('EA_PARAMS');

	$list = BitrixTasksInternalsTaskLogTable::getList(array(
		"select" => array("ID"),
		"filter" => array(
			"=TASK_ID" => $taskId,
		),
	));

	while ($item = $list->fetch()) {
		$result = BitrixTasksInternalsTaskLogTable::delete($item);
	}
}