Django snippets

# Template - you can put this code on admin/base.html or on
# admin/change_form.html, as you want

<script src="{{ MEDIA_URL }}js/jquery.js" type="text/javascript"></script>
<script type="text/javascript">
$(document).ready(function() {
    $('input[type=file]').each(function() {
        $(this).after(' <input type="checkbox" name="clear_image_'+$(this).attr('name')+'"/> Clear');
    });
});
</script>

# Your ModelAdmin

from django.contrib.admin.options import ModelAdmin

class MyModelAdmin(ModelAdmin):
    def save_form(self, request, form, change):
        """Deletes the file from fields FileField/ImageField if
        their values have changed"""

        obj = form.instance
        if obj:
            for field in obj._meta.fields:
                if not isinstance(field, FileField):
                    continue
               
                path = getattr(obj, field.name, None)
                if path and os.path.isfile(path.path):
                    if field.name in form.changed_data or form.data.get('clear_image_'+field.name, ''):
                        os.unlink(path.path)
                        setattr(obj, field.name, None)
           
        return super(MyModelAdmin, self).save_form(request, form, change)