无法删除django中的表单内联表单集

from django.forms import inlineformset_factory
from django.shortcuts import render, redirect
from .models import ParentModel, ChildModel

def edit_parent(request, parent_id):
    ParentChildFormSet = inlineformset_factory(ParentModel, ChildModel, fields=('field1', 'field2'), extra=1)
    parent = ParentModel.objects.get(id=parent_id)
    formset = ParentChildFormSet(instance=parent)

    if request.method == 'POST':
        formset = ParentChildFormSet(request.POST, instance=parent)
        if formset.is_valid():
            formset.save()
            # 删除表单内联表单集中的数据
            formset.delete()
            return redirect('success')

    return render(request, 'edit_parent.html', {'formset': formset})