class MyForm(forms.ModelForm):

    def __init__(self, *args, **kwargs):
        super(MyForm, self).__init__(*args, **kwargs)
for key, field in self.fields.items():
    self.fields[key].required = False


class Meta:
    model = MyModel
exclude = []
field_1 = forms.CharField(label='field_1_label')
field_2 = forms.CharField(label='field_2_label', widget=forms.Textarea(
    attrs={'class': 'width100 h4em'}))
field_3 = forms.CharField(label='field_3_label', widget=forms.TextInput(
    attrs={'class': 'width100'}))
field_4 = forms.ModelChoiceField(label='field_4_label', queryset=
    AnotherModel.objects.all().order_by('order'))


class MyForm_Extended_1(MyForm):
    field_1 = None


class MyForm_Extended_2(MyForm):


    class Meta:
        model = MyModel
exclude = ['field_1']
Django: удалить поле из подкласса формы