It's not clear what you want the result to look like, but the output of this looks OK to me:
<div class="list-group">
<a href="#demo6" class="list-group-item" data-toggle="collapse" data-parent="#MainMenu">Gallaries</a>
<div class="collapse" id="demo6">
<a href="#SubMenu1" class="list-group-item" data-toggle="collapse" data-parent="#SubMenu1">Shridharani Gallery<i class=" fa-caret-down"></i></a>
<a href="#SubMenu1" class="list-group-item" data-toggle="collapse" data-parent="#SubMenu1">Triveni Gallery<i class=" fa-caret-down"></i></a>
<a href="#SubMenu1" class="list-group-item" data-toggle="collapse" data-parent="#SubMenu1">Sculptor Court<i class=" fa-caret-down"></i></a>
<a href="#SubMenu1" class="list-group-item" data-toggle="collapse" data-parent="#SubMenu1">Open Air Gallery<i class=" fa-caret-down"></i></a>
<a href="#SubMenu1" class="list-group-item" data-toggle="collapse" data-parent="#SubMenu1">Garden Gallery<i class=" fa-caret-down"></i></a>
</div>
</div>
http://jsfiddle.net/xtw2h4wj/[
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