Novice django, deletes the uploaded picture in the admin background only deletes the record of the database, but the picture still exists in the media/img folder. How to deal with this?

models.py
class HomePageProductPictureDisplay(models.Model):
    description = models.CharField("", max_length=200)
    img = models.ImageField(upload_to="img")  -sharp upload_to

    class Meta:
        verbose_name_plural = ""
        verbose_name = ""

    def __str__(self):
        return self.description