How to remove an event handler in VB.NET

You can do so using the RemoveHandler operator, as such:

Private Sub Panel1_click(ByVal sender As Object, ByVal e As System.EventArgs)
    Dim panel As Panel = CType(sender, Panel)
    RemoveHandler panel.Click, AddressOf Panel1_Click
End Sub

The same way you added it:

RemoveHandler s.Click, AddressOf Panel1_Click

Reference