TwitterRT OauthToken Verification


I’m developing Windows Store application my app allow to share the message to Twitter and Facebook i’m Using Facebook SDK and TwitterRT SDK. Facebook access token stored in local storage and i check token validation using some methods.but i don’t know how to check Twitter OauthToken validity and once its authorized then each time its return OauthToken and user details how to remove the authentication(While user sign out from my app Twitter authentication should be deactivate).