取消关注Twitter配置文件PHP脚本不起作用

I'm not able to unfollow accounts. The code is returning the account details of user whom I want to unfollow. Application is created by Account A, with read/write/Access Direct Messages. I have logged in with a Account B, authenticated and returned back. Using below code I want to unfollow.

$key=$twitter_id_whom_i_want_to_unfollow; 

$settings = array(
    'oauth_access_token' => YOUR_ACCESS_TOKEN,
    'oauth_access_token_secret' => YOUR_ACCESS_TOKEN_SECRET,
    'consumer_key' => YOUR_CONSUMER_KEY,
    'consumer_secret' => YOUR_CONSUMER_SECRET
);
$requestMethod = 'POST';
$postfields = array(
        'user_id' => $key
            );
$url = 'https://api.twitter.com/1.1/friendships/destroy.json'; /*Remove that user from friends*/
$twitter = new TwitterAPIExchange($settings);
$profile=$twitter->buildOauth($url, $requestMethod)
         ->setPostfields($postfields)
         ->performRequest();
$profile=json_decode($profile); 
echo '<pre>';print_r($profile);

This prints $twitter_id_whom_i_want_to_unfollow account details. Not able to understand how to deal with it. I'm developing a web app like crowdfire

If I use same script to unfollow from $twitter_id_whom_i_want_to_unfollow account, it works, but not from any other account.