There are several ways to achieve this...
If you want to do a 'disable all' then you can - I use the web interface so, if you're using the app, the procedure might be different - select 'Quick Links', 'Subscribed Threads', 'Delete All' and that will remove you from all the threads you've subscribed to. They're there in a folder, so you can also delete them individually.
Another way is that, in the emails that you receive, there's a link at the bottom of the email that allows you disable just that particular notification.
Tim