The method Remove(key: String) is supposed to return true if the key-value pair is removed, as stated in the documentation. But for the android implementaiton, it always returns false.

By looking at the code, the problem is clear. The return value is hard coded to be always false.

        static bool PlatformRemove(string key)
        {
            var context = Platform.AppContext;

            key = Utils.Md5Hash(key);
            Preferences.Remove(key, Alias);

            return false;
        }

I have located when the bug was first introduced in the commit: 4da4ea3.