You can edit your email subscription preferences and unsubscribe from various email lists you're signed up for by clicking the "Edit Email Subscriptions" link from your dashboard.
On the edit subscriptions page, you can see every email list you're signed up for, as well as details that tell you why you're subscribed to that list. You can report email lists as spam, and you can unsubscribe from them individually.
You can also unsubscribe from the transactional email that the Action Network sends you as you use the site. (For example, transactional email is the reminders we send you 24 hours before an event you've RSVPd for is to occur, or the thank you email we send you after you take action.) Click the button in the right sidebar to unsubscribe or resubscribe to transactional email.