You can specify a mail folder by its folder ID, or by its well-known folder name, if one exists.
Note You may not be able to delete items in the recoverable items deletions folder (represented by the well-known folder name recoverableitemsdeletions). See Deleted item retention and Clean up deleted items for more information.
// Code snippets are only available for the latest version. Current version is 5.x
var graphClient = new GraphServiceClient(requestAdapter);
await graphClient.Me.MailFolders["{mailFolder-id}"].DeleteAsync();
<?php
// THIS SNIPPET IS A PREVIEW VERSION OF THE SDK. NON-PRODUCTION USE ONLY
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$graphServiceClient->me()->mailFolders()->byMailFolderId('mailFolder-id')->delete()->wait();
# THE PYTHON SDK IS IN PREVIEW. FOR NON-PRODUCTION USE ONLY
graph_client = GraphServiceClient(request_adapter)
await graph_client.me.mail_folders.by_mail_folder_id('mailFolder-id').delete()