removing RichTextBox lines while keeping the colour of remaining lines in C#

Question

Consider a RichTextBox which has 400 lines and includes a number of words and lines in diffident colours.

Is it possible to remove the first 100 lines of this text b

Answer 1

.SelectedText = "" throws a Windows ding in my application

So I found a second solution which is to play with .Lines property

if (nbLines > maxLines)
{
    Array.Copy(rtfBox.Lines, 1,
               rtfBox.Lines, 0, rtfBox.Lines.Length - 1);
}