Hi Somil
two things:
1. you need to bind the combobox to the supplier property in your model.
<ComboBox selectionChange="onChange" selectedKey="{Supplier}"2. When you remove the rows, you have to be careful with for doing
for (var i = 0; i < items.length; i++)
instead you should be doing
for (var i = items.length - 1; i >= 0;--i)
Here is the working example
JS Bin - Collaborative JavaScript Debugging
Thanks
-D