How do I edit a WTForms FieldList to remove a value in the middle of the list

I am trying to create a screen that looks like this:

To do this I create a form (TemplateFormRow) and then put it into a FieldList item in a parent form (TemplateForm). My form code is as follows:

class TemplateFormRow(FlaskForm):
    col = StringField(label='Column Name')
    data_type = SelectField(label='Data Type',
                            choices=[("boolean", "boolean"), ("datetime", "datetime"),
                                     ("integer", "integer"), ("decimal", "decimal"), ("string", "string")])
    sequence = HiddenField()
    delete = SubmitField(label='Delete')


class TemplateForm(FlaskForm):
    rows = FieldList(unbound_field=FormField(TemplateFormRow), min_entries=1)
    add_row = SubmitField(label='Add Row')
    confirm = SubmitField(label='Confirm')

The goal is that when someone clicks the 'Delete' button on any row, I delete that row and present the form again without it. I finally got some Python / Flask code to make this work:

for ndx, this_row in enumerate(form.rows):
                if this_row.data['delete']:  # This was the row on which the person hit the delete button
                    # TODO: WTForms seems to say you shouldn't do the following, but it seems to work.
                    del form.rows.entries[ndx]
                    break

My problem is that the WTForms documentation for FieldList says, I think, that you're not supposed to do this...

Do not resize the entries list directly, this will result in undefined behavior. See append_entry and pop_entry for ways you can manipulate the list.

Their recommendations of using pop doesn't work for me as that pulls the last item off the list but I may need to pull the first, or a middle, item off.

So, what I'm doing works but, is it dangerous? Is there a better / approved way to do this? Thanks for your help!