class MyMoveForm(MoveForm):
    def clean(self):
        data = super().clean()
        if not data.get("new_location"):
            return data
        if self.request.user.is_superuser:
           return data

        # don't allow to create a new root node
        relative = data["relative"]
        first_or_right = data["first_or_right"]
        if not relative:
            raise ValidationError("You do not have the permission to move this page here!")
        elif first_or_right =='right' and not relative.parent:
            raise ValidationError("You do not have the permission to move this page here!")


@admin.register(models.Page)
class PageAdmin(ContentEditor, TreeAdmin):
    ...

    def move_view(self, request, obj):
        return self.action_form_view(
            request, obj, form_class=MyMoveForm, title=f"Move {obj}"
        )