SimpleMembershipProvider smp = new SimpleMembershipProvider();
smp.DeleteUser(UserName, true);

((SimpleMembershipProvider)Membership.Provider).DeleteAccount(UserName);    // deletes record from webpages_Membership table
((SimpleMembershipProvider)Membership.Provider).DeleteUser(UserName, true); // deletes record from UserProfile table

((SimpleMembershipProvider)Membership.Provider).DeleteAccount(UserName);    // deletes record from webpages_Membership table
((SimpleMembershipProvider)Membership.Provider).DeleteUser(UserName, true); // deletes record from UserProfile table

        
        [Authorize]
        public ActionResult DeleteUser(string UserName)
        {
            var roles = (SimpleRoleProvider)Roles.Provider;
            string[] usr = new string[] { UserName };
            string[] qRoles = roles.GetRolesForUser(UserName);  // Узнаём в каких ролях присутствует пользователь
            roles.RemoveUsersFromRoles(usr, qRoles);    // Вначале удаляем роль пользователя
            ((SimpleMembershipProvider)Membership.Provider).DeleteAccount(UserName);    // deletes record from webpages_Membership table
            ((SimpleMembershipProvider)Membership.Provider).DeleteUser(UserName, true); // deletes record from UserProfile table

            WebSecurity.Logout();
            return RedirectToAction("Index", "Home");
        }