Android 11 introduced a feature that places messages from messaging applications in the “Conversations” section of the message shadow. These messages are always at the top of the list, but it̵7;s easy to remove an app from this section.
To do so, when a message appears in the “Conversations” section, hold it down.
Touch the gear icon at the top right to open the “Settings” menu.
You are now in the notification settings for the given app. If the app supports the “Conversations” feature, you’ll see a list of people and groups in the top section; tap the one you want to delete.
Scroll down and select “Not a conversation.” This directly removes the item from “Conversations” and returns to the previous screen.
Some apps do not support “conversations” properly, but they still appear in that section; at the time of writing, Facebook Messenger is one of these. The image below is what you see when you press and hold a notification in Facebook Messenger.
You can still remove these apps from Conversations. Just tap the gear icon at the top right of the extended notification panel.
Turn off the “Conversation Section” switch.
That’s all! If you ever want to adjust the notification settings for an app, just press and hold to get started.