Disable Discord dock badge

It usually means you have an unread message in a channel. You can disable it by going to your System Preferences -> Notifications -> Discord -> Uncheck the "Badge app icon".

Discord also doesn't show up for me in System Preferences -> Notifications, however there are two places where Discord notification settings are, both accessible from the app.

From the top ribbon, click Discord > Preferences and there's a Notifications menu. From there you can disable Desktop notifications.

Additionally, if you right click each channel you're in you can see the per-channel notification settings.

Finally, in order to actually clear the badge after I turned notifications off, I right clicked each channel and clicked "Mark as read".

If anyone in any of the servers you are part of tags @everyone, then there'll be a notification. Literally the only time the dot badge disappears for me is if I mute every server for x hours. Doesn't matter if you've set notifications to Only @ Mentions.

Also, make sure you go to your Inbox tray icon and tick all Unreads, and change the settings for Mentions to not Include @everyone mentions.

Discord is rough if you are a server manager, cos you literally cannot use the dock icon to just see important messages on your own server unless everything else is muted.

Discord now seems to have a setting to disable this useless badge icon!

Go to Discord > Settings > App Settings > Notifications > Enable Unread Message Badge: