' This is a form with 2 buttons, one to create the form and one to close the other form.
Public Class Form2

    Public Class myForms
        Public Shared forms(4) As System.Windows.Forms.Form
    End Class

    Public Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        myForms.forms(0) = Me
    End Sub


    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim myform1 As New Form4
        myform1.Show()
        myForms.forms(1) = myform1

        Dim myform2 As New Form4
        myform2.Show()
        myForms.forms(2) = myform2

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        myForms.forms(1).Close()
        myForms.forms(2).Close()

        myForms.forms(1) = Nothing
        myForms.forms(2) = Nothing
    End Sub
End Class