Upgrade your Membership
As a Free Member you can click on "Upgrade Membership" which is under your banner in your My Profile page.
Downgrade your Membership
As a Premium Member you can go into the user dropdown menu and click Membership.
Once on the Membership page click on "Downgrade Anytime"
Cancel your Membership
Contact customer service at email@example.com - you will need to have a Free account to Cancel your account. Follow steps to downgrade your account if you currently are a Premium Member.