One key indicator of knowing whether an account has been deleted is by checking out the username. Changes to the username occur when someone goes through the process of deleting their account. It is important to mention that Discord gives users the option to disable rather than delete an account.
The easiest way to report someone on Discord is to simply tell a moderator of the server that the inappropriate behavior occurred in. If you want to report something to Discord’s own Trust & Safety team, you’ll need to turn on the app’s Developer Mode.