public static void Run() { // ExStart:DeleteTaskOnExchange // Create instance of ExchangeClient class by giving credentials IEWSClient client = EWSClient.GetEWSClient("https://outlook.office365.com/ews/exchange.asmx", "testUser", "pwd", "domain"); // Get all tasks info collection from exchange ExchangeMessageInfoCollection tasks = client.ListMessages(client.MailboxInfo.TasksUri); // Parse all the tasks info in the list foreach (ExchangeMessageInfo info in tasks) { // Fetch task from exchange using current task info ExchangeTask task = client.FetchTask(info.UniqueUri); // Check if the current task fulfills the search criteria if (task.Subject.Equals("test")) { //Delete task from exchange client.DeleteTask(task.UniqueUri, DeleteTaskOptions.DeletePermanently); } } // ExEnd:DeleteTaskOnExchange }