How do I stop receiving email notifications when new submissions are made?

You can delete the form Notifiers if you like.

user guide: How-to-Delete-Notifications-Autoresponder

The form will stop sending the Submission Emails when absent on the form.

Just to be clear, the submission Notification Email is an important part of the form... so I am not sure why you wanted to stop getting them.

You can also just create some email rules instead in your inbox to archive the email messages -- which you might find of used in the future.

Let us know how we can be of further assistance.

Thanks.