How do I turn off notifications?

From my phone's settings

1. Open the Settings app and tap 'Notifications'.
2. Tap the app of which notifications you want to silence.
3. Slide the 'Allow Notifications' toggle to the 'Off' position.

From the Mondly app

1. Tap on your profile (the circle in the top-left corner)
2. Tap 'Learning reminders' 
3. Toggle off 'Turn off reminders'