How to remove all characters from StringBuilder in C#

// C# program to demonstrate
// the Clear() Method
using System;
using System.Text;

class GFG {

    // Main Method
    public static void Main(String[] args)
    {
        // Creating a StringBuilder object
        StringBuilder sb1 = new StringBuilder("GeeksforGeeks");

        // printing the length of "GeeksforGeeks"
        Console.WriteLine("The String is: {0} \nTotal characters -- {1}",
                                             sb1.ToString(), sb1.Length);

        // using the method
        sb1.Clear();

        // printing the length of "GeeksforGeeks"
        Console.WriteLine("The String is: {0} \nTotal characters -- {1}",
                                             sb1.ToString(), sb1.Length);

        sb1.Append("This  is C# Tutorials.");

        // printing the length of "GeeksforGeeks"
        Console.WriteLine("The String is: {0} \nTotal characters -- {1}",
                                             sb1.ToString(), sb1.Length);
    }
}