Hey Your_average_minecrafter,
We actually have a "mark as read" button. If you hover on a notification, there is a little tick symbol on the right side that you can click on to mark the notification as read.
![screenshot of unread WurstForum notification with tick symbol](https://i.imgur.com/ZMCd9jV.png)
There are also "mark all as read" and "delete all notifications" buttons in the top-right corner of the notification box.
![screenshot of WurstForum notification box header with tick and trash can symbols](https://i.imgur.com/igaACXx.png)
Unfortunately there is no way to delete only a single notification. That's just a limitation of Flarum's notification system.
Hope this helps!