Hi Gurjinder Jeet Singh,
as far as I know Liferay native integration with OpenAM is based on a servlet filter and auto login classes that can manage the SSO login and Single logout only when logout is started from Liferay. If you perform a SSO login and the a logout on OpenAM or by another application that can handle Single Logout, Liferay still keep your session and doesn't logout the user because Liferay use jsessionid and doesn't not very your session on open is valid on every request.
If you need this functionality I suggest you to try configuring OpenAM Policy Agent.
You can find useful info here:
OpenAM Policy Agent Integration.
Bye,
Denis.
