Access textbox inside CreateUserWizard

I have textbox named txtmob this is inside CreateUserWizard and I have button named btnmore outside CreateUserWizard I need to hide the txtmob when I click btnmore
Imports System.Data.SqlClient Partial Class Account_Register Inherits System.Web.UI.Page Protected Sub CreateUserWizard1_CreatedUser(ByVal sender As Object, ByVal e As EventArgs) Handles CreateUserWizard1.CreatedUser ' Get the UserId of the just-added user Dim newUser As MembershipUser = Membership.GetUser(CreateUserWizard1.UserName) Dim newUserId As Guid = DirectCast(newUser.ProviderUserKey, Guid) 'Get Profile Data Entered by user in CUW control Dim FirstName As String = DirectCast(CreateUserWizard1.CreateUserStep.ContentTemplateContainer.FindControl("txtFirstName"), TextBox).Text Dim FamilyName As String = DirectCast(CreateUserWizard1.CreateUserStep.ContentTemplateContainer.FindControl("txtFamilyName"), TextBox).Text ...