$re = '/(?<=")\t+(?=.+")/m';
$str = '_record_number record_id id_testing Notes IntakeComplete
111 6 5 " We will not be testing because of covid 19" 1
222 6 5 " We will not be "testing because of covid 19" 1
333 6 5 " We will not be "testing" because of covid 19" 1';
$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