at the moment there is no control from the back-end. When you refer to:
Account.DateOfBirth This will just change the text in the label for the DOB.
What I suggest you do is edit the Modules/CustomerRegister.ascx
and remove fields you do not require, you will then need to remove relivant coding CS file.
eg:
Modules/CustomerRegister.ascx
Remove
<tr class="Row">
<td class="ItemName">
<%=GetLocaleResourceString("Account.DateOfBirth")%>:
</td>
<td class="ItemValue">
<asp:TextBox runat="server" ID="txtDateOfBirth" />
<asp:ImageButton runat="Server" ID="iDateOfBirth" ImageUrl="~/images/Calendar_scheduleHS.png"
AlternateText="Click to show calendar" /><br />
<ajaxToolkit:CalendarExtender ID="cDateOfBirthButtonExtender" runat="server" TargetControlID="txtDateOfBirth"
PopupButtonID="iDateOfBirth" />
</td>
</tr>
And then remove relivant code behind Modules/CustomerRegister.ascx.cs
Comment Out
Line: 154 //TextBox txtDateOfBirth = (TextBox)CreateUserWizardStep1.ContentTemplateContainer.FindControl("txtDateOfBirth");
Line: 184 //try
Line: 185 //{
Line: 186 // DateTime dateOfBirth = DateTime.Parse(txtDateOfBirth.Text);
Line: 187 // customer.DateOfBirth = dateOfBirth;
Line: 188 //}
Line: 189 //catch
Line: 190 //{
Line: 191 // customer.DateOfBirth = null;
Line: 192 //}
You will need to remember that you will have to edit other files within the store front like Modules/CustomerInfo and so on.
Hope this helps in some way.
mike..