If you have an account level price plan already set, you cannot choose to lower your storage length. If your collection order was used to set your account level price plan, you can decrease or increase your account storage length by editing your collection order from the My Stuff page of your account. Find out if you have an account level price plan here.
You can choose to return your boxes earlier than your account storage end date. Find out more about the prices associated with returning early here.
You can choose to extend your price plan and get an even better price. Find out more about extending your price plan here.