The place to manage your notifications is on your user settings page. Click your user icon in the upper right of any screen and choose "Settings". From that screen, expand the "Notifications" section.
You'll always see the two options for getting notified of changes to daily or class attendance. Below, you'll see any student group subscriptions you have, and whether those subscriptions are via web notifications, email, or both.
To make changes to the group subscriptions you have, tick or untick the boxes as desired. Unticking both web and email boxes will eliminate all notifications for that group, and will remove that entry from your user settings page. Make sure you save all your changes by clicking the green disk icon in the upper right.