Remove drawn object in C# windows forms

Questions:

How can I delete (clear) lines that were made useing Graphics.DrawLine() ?
 
Drawn a circle in windows form. I want the remove the drawn object in C# windows forms.
Pen pen = new Pen(Color.Black, 3); Graphics gr = this.CreateGraphics(); gr.DrawEllipse(pen, 5,5,20,20);


Quick Answer:

this.Invalidate();

Cheers,

Venkatesan Prabu . J

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