When using easy_thumbnails on django you want to delete created thumbnails in two cases: 1) you update or "clean" the image file of the model 2) you delete the model instance. Using Signals, this is pretty easy This code is tested and working when updating one item, removing it and it also works when bulk deleting

models.py

from easy_thumbnails.models import Source, Thumbnail
from django.db import models
from django.db.models.signals import pre_delete, pre_save
from project_package import settings

class Project(models.Model):
    name = models.CharField("Name", max_length=255)
    main_image = models.ImageField("Main Image", blank=True, null=True, upload_to='uploads')

    def __unicode__(self):
        return self.name

    def clean_thumbnails(self, delete_source=False):
        if self.main_image:
            sources = Source.objects.filter(name=self.main_image.name)
            if sources.exists():
                for thumb in Thumbnail.objects.filter(source=sources[0]):
                    try:
                        os.remove(os.path.join(settings.MEDIA_ROOT, thumb.name))
                        thumb.delete()
                    except Exception, e:
                        print "error " + e.message
                if delete_source:
                    for source in sources:
                        source.delete()
                        
                        
""" Signals """


def pre_delete_project(sender, instance, *args, **kwargs):
    instance.clean_thumbnails(True)


def pre_save_project(sender, instance, *args, **kwargs):
    saved = sender.objects.filter(id=instance.id)
    if saved.exists():
        saved[0].clean_thumbnails()
        
pre_delete.connect(pre_delete_project, Project)
pre_save.connect(pre_save_project, Project)