If you want to change or cancel your subscription, go to your Settings, then click the Subscription tab, then click the Change Subscription button.  The following screen will appear:

Any changes you make will take effect at the end of the current term.  For example, if you are currently on a yearly plan and you switch to monthly, then the switch will occur at the end of the yearly term.

If you want to cancel, then the following screen will popup:

As per the on-screen guidance, please be aware that you need to download a copy of your vaultbox first.  You will continue to be able to access vaultbox, but only in the capacity of a Deputy.