In the My3 App, click on the ADD ONS tab.
The add ons page is tailored to your account and will show you the options that best suit your needs.
Here you may see a list of any previously purchased ADD ONS along with any additional ADD ONS available for purchase. Where an add on is removable you will see an X icon next to the add on name.
Depending on your account type you may be prompted to message a customer care agent who will assist you in managing your add ons.