如何从应用程序类中删除Auth Token用于android中Twitter应用程序中的注销功能

public class TwitterAuthToken {
    private String token;
    private String secret;

    public TwitterAuthToken(String token, String secret) {
        this.token = token;
        this.secret = secret;
    }

    public String getToken() {
        return token;
    }

    public String getSecret() {
        return secret;
    }

    public void clear() {
        token = null;
        secret = null;
    }
}

public class TwitterManager {
    private static TwitterManager instance;
    private Twitter twitter;
    private TwitterAuthToken authToken;

    private TwitterManager() {
        // Initialize Twitter SDK
        TwitterConfig config = new TwitterConfig.Builder(App.getInstance())
                .logger(new DefaultLogger(Log.DEBUG))
                .twitterAuthConfig(new TwitterAuthConfig(TWITTER_KEY, TWITTER_SECRET))
                .debug(true)
                .build();
        Twitter.initialize(config);
        twitter = Twitter.getInstance();
    }

    public static TwitterManager getInstance() {
        if (instance == null) {
            instance = new TwitterManager();
        }
        return instance;
    }

    public void setAuthToken(String token, String secret) {
        authToken = new TwitterAuthToken(token, secret);
    }

    public void clearAuthToken() {
        if (authToken != null) {
            authToken.clear();
            authToken = null;
        }
    }

    public boolean isAuthenticated() {
        return authToken != null && !TextUtils.isEmpty(authToken.getToken()) && !TextUtils.isEmpty(authToken.getSecret());
    }

    public void logout() {
        clearAuthToken();
        twitter.logOut();
    }
}

TwitterManager.getInstance().logout();