title: How to remove external identity from cognito user id and also check whether current cognito id is merged with any external identities or not?
body: <p>I have linked external identity of Facebook with cognito id using below code:</p>
  
  <pre><code>credentialsProvider?.logins = ["graph.facebook.com" : FBSDKAccessToken.currentAccessToken().tokenString]
  credentialsProvider?.refresh()
  </code></pre>
  
  <p>Taken reference from : <a href="http://docs.aws.amazon.com/cognito/devguide/identity/external-providers/facebook/" rel="nofollow">http://docs.aws.amazon.com/cognito/devguide/identity/external-providers/facebook/</a>.
  Now I want that if user logout from Facebook then also want to remove Facebook identity from that cognito id, want to keep same cognito id but just want remove that external identity . How to do that? Also I want to check first that whether any external identity is merged with that id or not? Note that I just want to delete this Facebook login identity not want to delete whole identity or anything else.</p>