Delete parent with children in one to many relationship

I have a .NET4.0 application with Entity Framework 5.0 e Sql Server CE 4.0.

I have two entities with a one to many (parent/child) relationship. I've configured it to cascade delete on parent removal, but for some reason it doesn't seem to work.

Here is a simplified version of my entities:

    public class Account
    {
        public int AccountKey { get; set; }
        public string Name { get; set; }

        public ICollection<User> Users { get; set; }
    }

    internal class AccountMap : EntityTypeConfiguration<Account>
    {
        public AccountMap()
        {
            this.HasKey(e => e.AccountKey);
            this.Property(e => e.AccountKey).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
            this.Property(e => e.Name).IsRequired();
        }
    }


    public class User
    {
        public int UserKey { get; set; }
        public string Name { get; set; }

        public Account Account { get; set; }
        public int AccountKey { get; set; }
    }

    internal class UserMap : EntityTypeConfiguration<User>
    {
        public UserMap()
        {
            this.HasKey(e => e.UserKey);
            this.Property(e => e.UserKey).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
            this.Property(e => e.Name).IsRequired();


            this.HasRequired(e => e.Account)
                .WithMany(e => e.Users)
                .HasForeignKey(e => e.AccountKey);
        }
    }

    public class TestContext : DbContext
    {
        public TestContext()
        {
            this.Configuration.LazyLoadingEnabled = false;
        }

        public DbSet<User> Users { get; set; }
        public DbSet<Account> Accounts { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Conventions.Remove<PluralizingTableNameConvention>(); modelBuilder.Conventi