Still receiving Facebook messenger notifications even though the app was deleted from watch

Hi

How notifications are delivered from apps that remain installed on your iPhone depends on the status of your devices and your settings. With Wrist Detection enabled, in order to bring notifications to your attention as soon as possible:

• If your iPhone is unlocked, you will receive notifications on your iPhone instead of on your watch.
• If your iPhone is locked or asleep and your watch is unlocked (regardless of whether the watch screen is asleep or awake) and on your wrist, you will receive notifications on your watch.
• If your watch is locked or has Do Not Disturb enabled, notifications will go to your iPhone.

To stop notifications from Messenger from being shown on your watch:

On your iPhone, in the Watch app, go to: My Watch (tab) > Notifications > turn off the mirror iPhone alerts option for Messenger.

More information:

Notifications on your Apple Watch - Apple Support

The notifications are still coming from the Facebook app. Messenger was a separate app.

So if you're receiving chat notifications in Facebook, when you delete Messenger it will just default back to your Facebook app. Go in to the settings and adjust those.