如何去掉select中的搜索框？


各位大神，这个搜索框怎么去掉？
代码如下：
<div class="row">
                  <div class="col-md-12">
                    <div class="form-group">
                      <label class="col-md-2 control-label">资产分类</label>
                      <div class="col-md-10">
                        <select id="roleNameList" class="form-control select2" style="width:695px"  placeholder="角色">
                          
                          <option >土地、房屋及构筑物</option>
                          <option >计算机设备及软件</option>
                          <option >办公设备</option>
                          <option >车辆</option>
                          <option >图书档案设置</option>
                        </select>
                        <span class="help-block"></span>
                      </div>
                    </div>
                  </div>
                </div>