How to fix problem: To call this method, the "Membership.Provider" property must be an instance of "ExtendedMembershipProvider"?

Because you are using SimpleMembership provider.
Either remove any other membership provider setting in web.config
Or
you add following setting in web.config file

Reference:
http://weblogs.asp.net/jgalloway/archive/2012/08/29/simplemembership-membership-providers-universal-providers-and-the-new-asp-net-4-5-web-forms-and-asp-net-mvc-4-templates.aspx