How should I delete branch from adjacency list in SQL Server?

Given a basic acyclic adjacency list like this:

What is the most effective way to handle deletions of branches?

My current approach uses a recursive CTE to find all descendant nodes and their depths (n). Then I iterate (ugh) over those depths in reverse and issue n deletes.

CREATE TABLE [dbo].[TreeNode](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [ParentNodeId] [int] NULL,
    [Name] [nvarchar](100) NOT NULL,
 CONSTRAINT [PK_TreeNode] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON, FILLFACTOR = 100) ON [PRIMARY]
) ON [PRIMARY]

GO

ALTER TABLE [dbo].[TreeNode]  WITH CHECK ADD  CONSTRAINT [FK_TreeNode_TreeNode] FOREIGN KEY([ParentNodeId])
REFERENCES [dbo].[TreeNode] ([Id])
GO

ALTER TABLE [dbo].[TreeNode]  WITH CHECK ADD  CONSTRAINT [CK_TreeNode_Id_ParentNodeId] CHECK  (([Id]<>[ParentNodeId]))
GO

ON DELETE CASCADE won't work here because it isn't allowed in self-referencing FKs