This looks like bad user experience to me. From what I can see you can both delete your presentations, and delete your account. If there was warning saying all your presentations will be made public if you do not delete them, with a checkbox to acknowledge the warning, rather than agree to it a condition no one would be getting upset. Obviously they could improve it further by giving you the option to choose what to delete / keep and the option to cancel the subscription and delete the whole account in one go. There docs say you must cancel the subscription before deleting you account or you will continue to be charged, which is just awful.