1message.delete({timeout: 5000 , reason: "system"})

1@client.event
2async def on_message(message):
3    await message.delete()

1"create a variable called id"
2var id
3"then inside your client message statement change id ->  id = message.id"
4client.on('message', message => {
5  id = message.id
6});
7"inside your command type  message.fetch(id).then(msg => msg.delete());"
8  if (message.content === !test)
9      message.fetch(id).then(msg => msg.delete());      
10}});

1import discord.ext
2
3bot = commands.Bot(";")
4
5@bot.event 
6async def on_message(message):
7    if message.content.upper().startswith(";SAY"):
8        args = message.content.split(" ")
9        await bot.send_message(message.channel, "%s" % (" ".join(args[1:])))
10        await bot.delete_message(message)
11