VB.NET Remove Item in ComboBox after placing in ListBox

Question

How can I remove item in comboBox after I choose it and put into listBox.

Here's my code. Please help me.

Imports System
Imports System.Data
Imports System.Data.SqlClient
Public Class frmAdvancePayment


    Private Sub frmAdvancePayment_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        lstBillNum.Items.Clear()
        Dim connection_string As String = "Data Source=.\sqlexpress;Initial Catalog=CreditAndCollection;Integrated Security=True"
        Dim connection As New SqlConnection(connection_string)
        connection.Open()
        Dim sql As String = "select BillNum from tblBillingSched where Status ='Unpaid'"
        Dim da As New SqlDataAdapter(sql, connection_string)
        Dim dt As New DataTable
        da.Fill(dt)
        cmbBillNum.DataSource = dt
        cmbBillNum.DisplayMember = "BillNum"
        cmbBillNum.ValueMember = "BillNum"
        connection.Close()
    End Sub



    Private Sub btnGet_Click(sender As Object, e As EventArgs) Handles btnGet.Click
        lstBillNum.Items.Add(cmbBillNum.SelectedValue)
    End Sub

    Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
        lstBillNum.Items.Clear()
    End Sub

End Class

Answer 1

it's what you expect ?

   Private Sub ComboBox1_SelectedValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedValueChanged
           Dim index As Integer = ComboBox1.SelectedIndex
           ListBox1.Items.Add(ComboBox1.Items(index))
           ComboBox1.Items.RemoveAt(index)
       End Sub