You can only fill in your personal data if you apply for a full membership.

src/membership/forms.py

@@ -69,7 +69,7 @@ class RegistrationForm(MembershipForm):
         fields = ('first_name', 'last_name', 'username', 'email',
                   'username', 'gender', 'first_name', 'last_name', 'email',
                   'avatar',
-                  'website', 'membership', 'birthday', 'telephone',
+                  'membership', 'birthday', 'telephone',
                   'street_name',
                   'post_code', 'city'
                   )

src/membership/templates/membership/register_form.html

@@ -24,7 +24,7 @@
 
   <fieldset class="grid_5">
     <legend>{% trans "Club membership"%}</legend>
-    {% get_fieldset "membership, first_name, last_name, gender, birthday, street_name, post_code, city, telephone, website" from form as form2 %}
+    {% get_fieldset "membership, first_name, last_name, gender, birthday, street_name, post_code, city, telephone" from form as form2 %}
     {% with form2 as form %}{% include "form.html" %}{% endwith %}
   </fieldset>
 
@@ -36,4 +36,18 @@
     </p>
   </div>
 </form>
+<script type="text/javascript">
+function togglePersonalData(event) {
+    var membership = document.getElementById("id_membership").checked;
+    var input_elements = ["id_first_name", "id_last_name", "id_gender", "id_birthday", "id_street_name", "id_post_code", "id_city", "id_telephone"];
+    for (var i = 0; i < input_elements.length; i++) {
+      element_id = input_elements[i]
+      element = document.getElementById(element_id);
+      element.disabled = !membership;
+    };
+};
+
+document.addEventListener('DOMContentLoaded',function() {document.querySelector('#id_membership').onchange=togglePersonalData;},false);
+togglePersonalData();
+</script>
 {% endblock %}