drop_unnecessary_tables.py

#  get all the unmanaged models
from django.db import connection
tables = connection.introspection.table_names()
seen_models = connection.introspection.installed_models(tables)
managed_tables = set([m._meta.db_table for m in seen_models])
extra_tables = set(tables) - managed_tables
cursor = connection.cursor()
for table in extra_tables:
    try:
        cursor.execute('DROP TABLE %s' % table)
    except Exception as e:
        print "Failed to drop %s for %s error with message %s" % (table, e, e.message)