1. Go to Google Classroom
2. Go to the main menu (3 horizontal lines) in the top left corner.
3. Select "Settings"
4. Under notifications turn off "Work and other posts from teachers." You can also turn off "Due-date Reminders..." (You are still responsible for your due dates of course). Please do not change any other settings as they are essential.
This will mean you will not longer get New Assignment or Due Date emails! Do read the Graded and Comment emails.