Using checkboxlist to update registry?

I have a check list box that has 5 directories that my program will call later. I want the user to be able to check what directories they want to use with a checklistbox. So far they can chose each item they want and it will be added but i want unchecked boxs to be removed from the registry

private void button1_Click(object sender, EventArgs e)
{
    textBox1.Text = "";
    foreach (object checkbox in checkedListBox1.CheckedItems)
    {
        textBox1.AppendText("Item is marked: " + checkbox.ToString() + "\n");
        RegBUP.SetValue(checkbox);
    }
}