The 20 GB for $20 Data Plus option is only available on the $28 /mo Base Plan.
Step 1: Open the CirclesCare app, click on the menu icon at the top left of your screen and go to the Customize Menu.
Step 2: By default, you are on the “BASE” page. Click on “PLUS” to show all your Plus settings options.
Step 3: Slide off the Plus option 20 GB for $20.
Et voilà, you’re done!
Please note that the deactivation will take effect from the first day of the following month onward - meanwhile, the Plus option will still be available on your plan!