You can modify your subscription by logging into your BURST account on the BURST website.
Once logged in you will go back to the home page and click the person icon 
This will bring you to your account and from here you can modify your subscriptions with BURST.
Modifying your subscription from a Laptop/Desktop
Once logged in you will see the person icon in the top Right-hand corner, This will bring you to your account and you can then select my Subscriptions tab from here you can edit your subscriptions with BURST.
Modifying your subscription from a Mobile device
You can modify your subscription by logging into your BURST account on the BURST website on your mobile device.
Once logged in you will go back to main page, Select the Menu from the top left-hand side, and the person icon or account.
This will bring up your account and you can view the My Subscriptions tab and from here you can edit your subscriptions with BURST.