Django unable to delete/clear data on form

i have a edit_profile view at my django application that also checks if the pgp key the users saves to his profile is in RSA format, Anyways if i add a profile avatar for the very first time it works like a charm, if i want to clear or delete it, im always jumping onto the execpt block and the user avatar remains unchanged. Well i dont see a clear reason why at the point can maybe smb give me a hint here:

validators.py

def default_image_file_extension(value):
    ext = os.path.splitext(value.name)[1]  # [0] returns path+filename
    valid_extensions = ['.jpg', '.jpeg', '.png']
    if not ext.lower() in valid_extensions:
        raise ValidationError(u'Unsupported file extension. Allowed types are: .jpg, .jpeg, .png')

def default_image_size(value):
    limit = 2 * 1024 * 1024
    if value.size > limit:
        raise ValidationError('File too large. Size should not exceed 2 MiB/MB.')

models.py

def get_file_path(instance, filename):
    ext = filename.split('.')[-1]
    filename = "%s.%s" % (uuid.uuid4(), ext)
    return os.path.join('media', filename)


def get_file_path_user_avatar(instance, filename):
    ext = filename.split('.')[-1]
    filename = "%s.%s" % (uuid.uuid4(), ext)
    return os.path.join('user_avatar', filename)

...


    class User(AbstractBaseUser):
    user = models.CharField(verbose_name='Username', max_length=20, unique=True)
    bio = models.TextField(verbose_name='Bio', blank=True, null=True, max_length=2500)
    pubpgp = models.TextField(verbose_name='Public RSA PGP Key - (ASCII-Armored)', blank=True, null=True, max_length=3000)
    avatar = fields.ImageField(
                              null=True,
                              blank=True,
                              upload_to=get_file_path_user_avatar,
                              validators=[default_image_size, default_image_file_extension],
                              dependencies=[FileDependency(processor=ImageProcessor(
                                  format='PNG', quality=99, scale={'max_width': 700, 'max_height': 700}))])

views.py

def edit_profile(request):
    if request.method == 'POST':
        form = UserForm(request.POST, request.FILES, instance=request.user)
        try:
            pubpgp = request.POST.get('pubpgp')
            if not pubpgp or PGPKey.from_blob(pubpgp.rstrip("\r\n"))[0].key_algorithm == PubKeyAlgorithm.RSAEncryptOrSign:
                if form.is_valid():
                   form.save()
                   messages.success(request, "Profile has been updated successfully.")
                   return redirect(reverse('home'))
                else:
                  print(form.errors)
                  return render(request, 'app_Accounts/edit_profile.html', {'form': form})
            else:
                messages.error(request, "Uuups, something went wrong, please try again.")
                return render(request, 'app_Accounts/edit_profile.html', {'form': form})
        except Exception as e:
            print(e.args)
            messages.error(request, "PGP-Key is wrong formated.")
            return render(request, 'app_Accounts/edit_profile.html', {'form': form})
    else:
        form = UserForm(instance=request.user)
        args = {'form': form}
        return render(request, 'app_Accounts/edit_profile.html', args)

forms.py

class UserForm(forms.ModelForm):

    class Meta:
        model = User
        fields = (
            'avatar',
            'bio',
            'pubpgp'
        )
    captcha = CaptchaField()

    field_order = ['avatar', 'bio', 'pubpgp']

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields['avatar'].label = mark_safe('Avatar:')
        self.fields['avatar'].help_text = mark_safe("<h4 class='help_text'>→ Choose a Avatar for your Profile (max. 2 MB)</h4>")
        self.fields['bio'].widget.attrs.update({'class': 'class-two-input-fields'})
        self.fields['bio'].help_text = mark_safe("<h4 class='help_text'>→ Something about you</h4>")
        self.fields['pubpgp'].widget.attrs.update({'class': 'class-two-input-fields'})
        self.fields['pubpgp'].label = 'Public PGP-key (Optional)'

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