how to disable bootstrap 3 form validation

bootstrap has an option to customize its components as per our need. My question is which component should i uncheck if i don't want bootstrap to be validating my forms. Because i have a form in which some fields can be left blank by the user. thank you.

my form :

<div class="container">
<div class="row">
 <div class="col-md-6">
 <form  action="sales.php" method="post" class="form-horizontal">

Customer ID

                           </div>
                            </div>

        <!-- Text input-->
                          <div class="form-group">
                            <label class="col-md-4 control-label" for="cname">Customer Name</label>  
                            <div class="col-md-6">
                            <input id="cname" name="cname" placeholder="" class="form-control input-md" required="" type="text">

                            </div>
                          </div>