This is a great question and has a lengthy answer. But I am glad you asked it as this will help others as well. To find all the options for your settings, click on your name (once you have logged in)-this will send you to your profile page. From here you can do several actions that will impact your account:
To edit your user name, email, password and general profile information, click on "Edit Profile" from the Action box to the right. You must scroll down and click save at the end to get back to your profile page to do steps 2-4.
To edit how and when you receive notifications from the community, select "Edit Preferences" from the Action box. It will open up the general preferences first so you will need to select the tab that says "Email Notification Preferences".
To manage what notifications you are already receiving, select "Manage Email Notifications" from the Action box to the right of your main profile page. This will populate a list of your current notifications. You will need to remove these if you don't want to receive them anymore (you can select individual notifications or clear them all at once).
To disable your account completely or ask any further questions or share concerns, email firstname.lastname@example.org with your request.
So...you can see this is not the most streamlined process; our community platform has improved upon this in the next upgrade, but for now, this is what we have. When we upgrade, it will be a much simplified process. Thanks for asking this very valuable question.