One at a time
When viewing a particular subject, or the subject list, you will see an "unsubscribe" link near the bottom of the page. Click on that to unsubscribe from whatever you are looking at.
Viewing all your subscriptions
By viewing your "user profile" you will see a list of all your subscriptions. In each case there will be an "unsubscribe" link next to it which you can click on.
Unsubscribing from all
If you wish to discontinue getting any notifications by email, view your user profile, and then click on "cancel all subscriptions".
Unsubscribing from notification of new subjects
View your user profile, and uncheck "Notify on new subject", and then save it.
When viewing a particular subject, or the subject list, you will see an "unsubscribe" link near the bottom of the page. Click on that to unsubscribe from whatever you are looking at.
Viewing all your subscriptions
By viewing your "user profile" you will see a list of all your subscriptions. In each case there will be an "unsubscribe" link next to it which you can click on.
Unsubscribing from all
If you wish to discontinue getting any notifications by email, view your user profile, and then click on "cancel all subscriptions".
Unsubscribing from notification of new subjects
View your user profile, and uncheck "Notify on new subject", and then save it.