Dan, you need some sort of moderation bot on the discord to log things in the action log such as deleted/edited messages. I suggest Dynobot for this. You can set up Dyno at www.dynobot.net. This bot also allows you to warn users with the ?warn command, ?Kick them, or ?ban them. Using these commands also allows them to being logged in a mod log that you can set up. The use of these commands is also logged in the action log.