这是Form2取消键的代码：

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        Form1.Show()
        Me.Close()
    End Sub
End Class

这是Form1的：
 Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged

    End Sub

    Private Sub TextBox2_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox2.TextChanged

    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If (TextBox1.Text = "yufan") And (TextBox2.Text = "yu13425413205") Then
            Form2.Show()
            Me.Hide()
        Else
            TextBox1.Text = ""
            TextBox2.Text = ""
            MsgBox("密码或用户名不正确,请重新输入")
            Exit Sub
        End If
    End Sub
谢谢哟！！