$re = '/Payment received NEFT \- Your account (\S+) has been credited for (\S+) from (\S+) vide Txn ref (\S+)/m';
$str = 'Payment received NEFT - Your account account_number has been credited for some_amount from some_sender vide Txn ref some_ref_num.';
$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