You can do this by going to the help link in your account and clicking to contact support. Choose 'Account Cancellation' from the drop down menu for the reason.
Or you can simply disable the one paid service you have enabled at this time, so you can still log into and access your account in the future. Do to so go to the My Account - My Payment Plans page. Click to 'see other plans' next to the one your enrolled in and you can discontinue it.
Yes, I do see that you have successfully deactivated the paid services. The only way you would be charged is if you enable a paid service or if you have active eBay listings that were launched through Vendio.