code: public static void purgeOAuthAccessTokens(RequestContext requestContext, String provider) {
      String key = String.format(PROVIDER_ACCESS_TOKENS, provider);
      HttpSession session = requestContext.getRequest().getSession();
      OAuthAccessToken[] accessTokens = (OAuthAccessToken[]) session.getAttribute(key);
      if (accessTokens != null) {
        session.removeAttribute(key);
      }
    }
docs: Purges all OAuth tokens from given provider
  
  @param requestContext request context
  @param provider provider