Hi Rahul Khinvasara,
I am afraid that by default RadComboBox encodes the text displayed in the input, so there is no option to see html in it.
If you populate the control with data that contains html tags, and you set the ValidateRequest property of the Page to "false" - you will see these tags in the input but they will look like a text string.
I made a simplified example in order to show you what happens in this case.
the Telerik team