If you clicked “allow” on a push notification popup or subscribed to push notifications for something else — groups, messages, etc. (note this is about BROWSER notifications, not email subscriptions), but no longer want to get them, unsubscribing is easy.
You’ll find a red bell in the lower left corner of your screen. Click it, and it will open your browser notification preferences. You can toggle some areas off and click “update” or “unsubscribe” to quit getting browser notifications.
If you have installed the Progressive Web App (PWA) to get notifications on mobile, quit getting notifications by uninstalling the app (though you can still use the bell prompt to make changes if you want to unsubscribe from certain areas.