Button to work as Backspace key in C#

Hello,
I am working on a windows form where i am taking a richtextbox and one button now what my query is that i want what so ever is written on my richtextbox must vanish one by one on the hit of that button

Example: lets say my richtextbox has 123 written on it then on the hit of that button first 3 must vanish and then 2 and then 1...

also i have enabled richtextboxs readonly property to true and i have set its max length to 10
i tried

private void button1_Click(object sender, EventArgs e)
        {
            richTextBox1.Text = "\b";
        }

but failed its working like

richTextBox1.Clear();

also i tried

if (richTextBox1.TextLength != 0)
            {
                int x = richTextBox1.TextLength;
                x += -1;
               
            }

but i dont know what to add further

ya and if the cursor is in the middle then too it must remove the text from its current location one by one

Please Please help me out

Thanks & Regards
Radix

Tags: C# (C# 2.0)