ninja.py

import datetime
from telethon import TelegramClient

api_id = 123456789
api_hash = 'abcdef123456789'

client = TelegramClient('session_name', api_id, api_hash)
client.session.report_errors = True
client.start()

delete_me_from = [
    "#BOFHers",
]

delta_time = 0.5 # Messages sent more than X hours ago

async def main():
    try:
        chats = client.iter_dialogs()
        async for chat in chats:
            if chat.name in delete_me_from:
                messages_exist = False
                deleted_any_message = False

                while True:
                    messages_exist = False
                    deleted_any_message = False

                    messages = client.iter_messages(chat, 100, from_user='me', wait_time=5)
                    now = datetime.datetime.now(tz=datetime.timezone.utc)

                    async for message in messages:
                        messages_exist = True

                        delta = now - message.date
                        time = delta.total_seconds() / 60 / 60

                        if time > delta_time:
                            print(message.text)
                            await message.delete(revoke=True)
                            deleted_any_message = True

                    if not messages_exist:
                        break

                    if messages_exist and not deleted_any_message:
                        break

    except Exception as e:
        pass

with client:
    client.loop.run_until_complete(main())