how to have a bot delete a message after a certain time code example

Example: discord bot remove message

import discord.ext

bot = commands.Bot(";")

@bot.event 
async def on_message(message):
    if message.content.upper().startswith(";SAY"):
        args = message.content.split(" ")
        await bot.send_message(message.channel, "%s" % (" ".join(args[1:])))
        await bot.delete_message(message)