Hey @darvell if you no longer want to use Giffgaff and they are taking money for Airtime Credit or a GOODYBAG then you need to turn OFF AUTO-Top Up or the Recurring Goodybag option.
So if you go to the following link:-
Then from this page you'll be able to Turn Off the AUTO-Top up and Recurring Goodybag option.
Then Giffgaff will stop recurring the Goodybag.
Then after 6months of no usage your sim card will automatically deactivate.
Hope this helps you and answers your question.