Remove the "Add" functionality in Django admin
You can customize the permission for each user group from within the admin interface: try going to /admin/auth/group and it should be straightforward from there.
This won't be as granular as the solution offered by the earlier answer, but it will take care of most of your needs without needing to customize the admin.
Is there a way to remove the "Add" functionality on the Django admin site? For certain entities, I only want the Django admin to be able to view them or change existing ones, but not add new ones.