core-bundle/src/Resources/contao/library/Contao/Model.php
public function delete()
	{
		$intPk = $this->{static::$strPk};

		// Track primary key changes
		if (isset($this->arrModified[static::$strPk]))
		{
			$intPk = $this->arrModified[static::$strPk];
		}

		// Delete the row
		$intAffected = Database::getInstance()->prepare("DELETE FROM " . static::$strTable . " WHERE " . Database::quoteIdentifier(static::$strPk) . "=?")
											   ->execute($intPk)
											   ->affectedRows;

		if ($intAffected)
		{
			// Unregister the model
			Registry::getInstance()->unregister($this);

			// Remove the primary key (see #6162)
			$this->arrData[static::$strPk] = null;
		}

		return $intAffected;
	}
public function delete()
	{
		$intPk = $this->{static::$strPk};

		// Track primary key changes
		if (isset($this->arrModified[static::$strPk]))
		{
			$intPk = $this->arrModified[static::$strPk];
		}

		// Delete the row
		$intAffected = Database::getInstance()->prepare("DELETE FROM " . static::$strTable . " WHERE " . Database::quoteIdentifier(static::$strPk) . "=?")
											   ->execute($intPk)
											   ->affectedRows;

		if ($intAffected)
		{
			// Unregister the model
			Registry::getInstance()->unregister($this);

			// Remove the primary key (see #6162)
			$this->arrData[static::$strPk] = null;
		}

		return $intAffected;
	}
Delete the current record and return the number of affected rows

@return integer The number of affected rows