How do I stop forum notifications to my email?

First, go to your Forum Account Profile and click the Edit button, scroll down to Notifications and open that section.  Now, uncheck "Automatically subscribe me to all topics I participate in", change the other drop-down to "None".  Now scroll down and click Save.

Next, at the top of your profile click the "Subscription" tab and remove any "Content you follow" that you don't need.  There are two more tabs next to that called, "Forums/Blogs you follow" and "Forum Thread Solutions you follow".  Remove any there you don't need.

That should solve your issue, but if not please let us know.

Thanks.