Mukund,
If you created custom menu, you have to write code by your's only. If you use Div to create menu, then you can change the color of the menu based on the authorization and CSS are useful to do it, or you can hide the menu using JQuery or Java script.
If you use default menu control in asp.net to display menu, please look the following link for solution.
http://forums.asp.net/p/1051380/1487722.aspx[
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Thanks