code: function( el ) {
        var _errorMessages = {};
        // if el is undefined ( This is the process of resetting all <form> )
        // or el is an object that has element more than one
        // and these elements are not checkbox
        if( typeof el === 'undefined' || ( el.length > 1 && el[0].type !== 'checkbox' ) ) {
          _errorMessages = this.form.querySelectorAll( '.'+ this.options.errorTemplateClass );
        }
        else {
          _errorMessages = this.parents( el[0] ).querySelectorAll( '.'+ this.options.errorTemplateClass );
        }
        for ( var i = 0, _lengthErrorMessages = _errorMessages.length; i < _lengthErrorMessages; i++ ) {
          this.window.close.call( this, _errorMessages[ i ] );
        }
        // set to handler false
        // otherwise at the next validation attempt, submit will not continue even the validation is successful
        this.handler = false;
      }
docs: Removes all error messages windows
  
  @param {object} or {void} el : form elements which have an error message window