An example of a WebCollect standard field that you might want to remove, would be the date of birth field.
The short answer is No, sorry. We are looking at giving organisations the option to configure some of the standard fields as compulsory or optional. When we do, it's possible that we will include a third option to remove/hide the field, as well. It won't apply to all WebCollect fields - email address will always be there, for example, because we use that as the unique identifying piece of information for people.
