public void DeleteDocumentById(string userId, string itemId)
        {
            var urlRoot      = $"https://graph.microsoft.com/v1.0/";
            var url          = $"{urlRoot}/users/{userId}/drive/items/{itemId}";
            var response     = _restClient.delResponse(url);
            var responseBody = response.Content.ReadAsStringAsync().ConfigureAwait(false).GetAwaiter().GetResult();

            if (!response.IsSuccessStatusCode)
            {
                throw new Exception(responseBody);
            }
        }
        public bool DeleteUser(string userPrincipalName)
        {
            //https://docs.microsoft.com/en-us/graph/api/user-post-users?view=graph-rest-1.0
            //https://graph.microsoft.com/v1.0/users/{user-id} DELETE
            //https://docs.microsoft.com/en-us/graph/permissions-reference#user-permissions
            //User.ReadWrite.All (delegated)
            var urlRoot      = $"https://graph.microsoft.com/v1.0/";
            var url          = $"{urlRoot}/users/{userPrincipalName}";
            var responseBody = _restClient.delResponse(url);

            Console.WriteLine(responseBody);
            return(true);
        }