Проверять только видимые поля с проверкой формы HTML5?

var checkbox = $('.account-type');

checkbox.on('change', function() {
  var checked = false;

  checkbox.each(function() {
    checked = checked || $(this).is(':checked');
  });

  checkbox.prop('required', !checked);
  
  $('div'+$(this).data('target') + ' :input').prop('disabled', !$(this).is(':checked'));
});

$('.frm-Submit').on('submit', submitAdminFrm);

function submitAdminFrm(e) {
  e.preventDefault(); // Prevnts default form submit.
  alert('Submit form!');
}

<script language = "javascript" src = "https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script language = "javascript" src = "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link rel = "stylesheet" href = "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<form name = "frmSave" id = "frmSave" class = "frm-Submit" autocomplete = "off">
  <div class = "form-group required">
    <label class = "control-label" for = "fname"><span class = "label label-primary">First Name:</span></label>
    <input type = "text" class = "form-control" name = "frm_firstname" id = "frm_firstname" placeholder = "Enter First Name" maxlength = "50" required>
  </div>
  <div class = "form-group required">
    <label class = "control-label" for = "lname"><span class = "label label-primary">Last Name:</span></label>
    <input type = "text" class = "form-control" name = "frm_lastname" id = "frm_lastname" placeholder = "Enter Last Name" maxlength = "50" required>
  </div>
  <div class = "form-group required">
    <label class = "control-label" for = "type"><span class = "label label-primary">Account Type:</span></label>
    <div class = "checkbox">
      <label for = "user">
          <input type = "checkbox" name = "frm_isuser" id = "frm_isuser" class = "account-type" data-toggle = "collapse" data-target = "#user-account" required> 
          <span class = "label label-default">User</span>
      </label>
      <label for = "staff">
          <input type = "checkbox" name = "frm_isstaff" id = "frm_isstaff" class = "account-type" data-toggle = "collapse" data-target = "#staff-account" required> 
          <span class = "label label-info">Staff</span>
       </label>
    </div>
  </div>
  <div id = "user-account" class = "collapse">
    <div class = "form-group required">
      <label class = "control-label" for = "active"><span class = "label label-default">Active User:<span></label>
      <select disabled class = "form-control" name = "frmSaveaccount_activeuser" id = "frmSaveaccount_activeuser" required>
        <option value = "">-- Select the option --</option>
        <option value = "0">No</option>
        <option value = "1">Yes</option>
      </select>
    </div>
  </div>
  <div id = "staff-account" class = "collapse">
    <div class = "form-group required">
      <label class = "control-label" for = "activestaff"><span class = "label label-info">Active Staff:<span></label>
      <select disabled class = "form-control" name = "frmSaveaccount_activestaff" id = "frmSaveaccount_activestaff" required>
        <option value = "">-- Select the option --</option>
        <option value = "0">No</option>
        <option value = "1">Yes</option>
      </select>
    </div>
  </div>
  <div class = "row">
    <div class = "form-group col-xs-12 col-sm-12 col-md-1 col-lg-1">
      <button type = "submit" name = "frmSaveaccount_submit" id = "frmSaveaccount_submit" class = "btn btn-primary">Submit</button>
    </div>
  </div>
</form>