Select the top checkbox to the right of Notification, then scroll down and select Delete Subscription from the checkbox. Your subscriptions will then all be removed.
You can also disable all new subscriptions automatically by going HERE and selecting Default Thread Subscription ModeWhen you post a new thread, or reply to a topic, you can choose to automatically add that thread to your list of subscribed threads, with the option to receive email notification of new replies to that thread. and changing it to Do not subscribe, and by finishing with clicking Save Changes.
Hope I've helped! Even though this is an old thread, might come in useful for someone else.