$re = '/(?:="|"\s+(?:\w+="|\/>))(*SKIP)(?!)|"/';
$str = '<record ObTime="2017-05-10T23:30" data_value="Ocean Park "The Sea WX" WA US" />
';
$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