Unable to Delete Airflow Dags using Airflow Session

Question

I want to write down airflow dags cleanup dag. I' https://github.com/teamclairvoyant/airflow-maintenance-dags for reference. I have written a cleanup DAG which takes all the dags and check their schedule, if it's once, it deletes the DAG. When I'm trying to run the cleanup dag, it is throwing sqlchemy error(Screenshot Attached). Please help me out with this error.

from airflow.operators.python_operator import PythonOperator
from airflow import settings
from datetime import timedelta
import os
import os.path
import socket
import logging
import airflow


DAG_ID = "AIRFLOW_CLEANUP_DAG"
START_DATE = airflow.utils.dates.days_ago(1)
SCHEDULE_INTERVAL = "@once"
DAG_OWNER_NAME = "PDM"
ALERT_EMAIL_ADDRESSES = []

ENABLE_DELETE = True

default_args = {
    "owner": DAG_OWNER_NAME,
    "depends_on_past": False,
    "email": ALERT_EMAIL_ADDRESSES,
    "email_on_failure": True,
    "email_on_retry": False,
    "start_date": START_DATE,
    "retries": 1,
    "retry_delay": timedelta(minutes=1),
}

dag = DAG(
    DAG_ID,
    default_args=default_args,
    schedule_interval=SCHEDULE_INTERVAL,
    start_date=START_DATE,
    catchup=False,
    description="Performing airflow cleanup",
)

if hasattr(dag, "doc_md"):
    dag.doc_md = __doc__
if hasattr(dag, "catchup"):
    dag.catchup = False


def cleanup_once_dags_fn(**context):
    logging.info("Starting to run cleanup Process")

    try:
        host_name = socket.gethostname()
        host_ip = socket.gethostbyname(host_name)
        logging.info("Running on Machine with Host Name: " + host_name)
        logging.info("Running on Machine with IP: " + host_ip)
    except Exception as e:
        print("Unable to get Host Name and IP: " + str(e))

    session = settings.Session()

    logging.info("Configurations:")
    logging.info("enable_delete:            " + str(ENABLE_DELETE))
    logging.info("session:                  " + str(session))
    logging.info("")

    dags = session.query(DagModel).all()
    entries_to_delete = []
    logging.info(f"Total dags :: {len(dags)}")
    for dag in dags:
        dag_schedule = dag.schedule_interval
        if dag_schedule == "@once" and dag.dag_id=='ba54206d-078c-42e8-a6b5-ad579e833364':
            entries_to_delete.append(dag)
    logging.info(f"Dags with once schedule {len(entries_to_delete)}")

    logging.info("Process will be Deleting the DAG(s) from the DB:")

    logging.info("Process will be Deleting " + str(len(entries_to_delete)) + " DAG(s)")

    if ENABLE_DELETE:
        logging.info("Performing Delete...")
        for entry in entries_to_delete:
            session.delete(entry)
        session.commit()
        logging.info("Finished Performing Delete")
    else:
        logging.warn("You're opted to skip deleting the DAG entries!!!")

    logging.info("Finished Running Clear Process")


cleanup_once_dags = PythonOperator(
    task_id="cleanup_once_dags", python_callable=cleanup_once_dags_fn, provide_context=True, dag=dag
)