Remove duplicates from unsorted linked list in csharp

Csharp program for Remove duplicates from unsorted linked list. Here problem description and explanation.

// Include namespace system
using System;
// Csharp Program to 
// Delete duplicate nodes in unsorted linked list
public class LinkNode
{
	public int data;
	public LinkNode next;
	public LinkNode(int data)
	{
		this.data = data;
		this.next = null;
	}
}
public class LinkedList
{
	public LinkNode head;
	public LinkNode tail;
	// Class constructors
	public LinkedList()
	{
		this.head = null;
		this.tail = null;
	}
	// Insert new element at end position
	public void insert(int value)
	{
		// Create new node
		var node = new LinkNode(value);
		if (this.head == null)
		{
			// Add first node
			this.head = node;
		}
		else
		{
			// Add new node at the last position
			this.tail.next = node;
		}
		// Make new tail 
		this.tail = node;
	}
	// Display all node value
	public void display()
	{
		if (this.head != null)
		{
			Console.Write("Linked List Element :");
			var temp = this.head;
			while (temp != null)
			{
				// Display node value
				Console.Write("  " + temp.data);
				// Visit to next node
				temp = temp.next;
			}
		}
		else
		{
			Console.WriteLine("Empty Linked list");
		}
	}
	public void removeNode()
	{
		if (this.head == null)
		{
			// When linked list empty
			Console.Write("Empty Linked list");
		}
		else
		{
			// Auxiliary variable
			var temp = this.head;
			LinkNode hold = null;
			LinkNode initial = null;
			LinkNode current = null;
			// Outer loop
			while (temp != null)
			{
				// New last node
				this.tail = temp;
				current = temp;
				initial = current.next;
				// Inner loop
				// Remove all node which value is similar to temp node
				while (initial != null)
				{
					if (temp.data == initial.data)
					{
						// Get remove node
						hold = initial;
					}
					else
					{
						current = initial;
					}
					// Visit to next node
					initial = initial.next;
					if (hold != null)
					{
						current.next = initial;
						// remove node
						hold = null;
					}
				}
				// Visit to next node
				temp = temp.next;
			}
		}
	}
	public static void Main(String[] args)
	{
		// new linked list
		var task = new LinkedList();
		// Add tested element
		task.insert(1);
		task.insert(2);
		task.insert(9);
		task.insert(4);
		task.insert(9);
		task.insert(3);
		task.insert(1);
		task.insert(7);
		task.insert(2);
		task.insert(1);
		Console.WriteLine("\nBefore Delete ");
		task.display();
		task.removeNode();
		Console.WriteLine("\nAfter Delete ");
		task.display();
	}
}

Output

Before Delete
Linked List Element :  1  2  9  4  9  3  1  7  2  1
After Delete
Linked List Element :  1  2  9  4  3  7