You mean remove the selected item(s)? The code below will remove all the
selected items in the ListBox. If the SelectionMode property of the ListBox
is set to allow selecting multiple items then this code will handle removing
all the selected items.
while (this.listBox1.SelectedIndices.Count > 0)
{
this.listBox1.Items.RemoveAt(this.listBox1.SelectedIndices[0]);
}