core-bundle/src/Resources/contao/drivers/DC_Table.php
public function deleteAll()
	{
		if ($GLOBALS['TL_DCA'][$this->strTable]['config']['notDeletable'])
		{
			throw new InternalServerErrorException('Table "' . $this->strTable . '" is not deletable.');
		}

		/** @var Session $objSession */
		$objSession = System::getContainer()->get('session');

		$session = $objSession->all();
		$ids = $session['CURRENT']['IDS'];

		if (\is_array($ids) && \strlen($ids[0]))
		{
			foreach ($ids as $id)
			{
				$this->intId = $id;
				$this->delete(true);
			}
		}

		$this->redirect($this->getReferer());
	}
public function deleteAll()
	{
		if ($GLOBALS['TL_DCA'][$this->strTable]['config']['notDeletable'])
		{
			throw new InternalServerErrorException('Table "' . $this->strTable . '" is not deletable.');
		}

		/** @var Session $objSession */
		$objSession = System::getContainer()->get('session');

		$session = $objSession->all();
		$ids = $session['CURRENT']['IDS'];

		if (\is_array($ids) && \strlen($ids[0]))
		{
			foreach ($ids as $id)
			{
				$this->intId = $id;
				$this->delete(true);
			}
		}

		$this->redirect($this->getReferer());
	}
Delete all selected records

@throws InternalServerErrorException