$re = '/\S+\s\d+\/\d+\/\d+/m';
$str = 'Buxtehude /1234 KundenAuftragEinsatzart1 698874/6387/01
KundenAuftragEinsatzart 698874/6387
Musterstadt /1234 KundenAuftragEinsatzart2 698874/6387/01
KundenAuftragEinsatzart3 698874/6387/01
KundenAuftragEinsatzart4 698874/6387/01';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php