You can disable the newsletter checkbox in your organization settings so it no longer appears during ticket purchases.
How to disable the newsletter checkbox
Click on your organization’s name in the top right and select Settings.
In the left bar select marketing.
You’ll find an option to hide the newsletter checkbox. Disable this option.
Note
The change is saved and applied immediately. New ticket buyers won’t see the newsletter checkbox anymore. If you want to enable it again later, simply toggle the setting back on.