In Scrum, the Product Owner is the only person who has the authority to cancel a Sprint. This is because the Product Owner is responsible for maximizing the value of the product and managing the Product Backlog, and they have the best understanding of the priorities and needs of the stakeholders. If a Sprint's goal becomes obsolete or irrelevant due to changes in the market or business needs, it is up to the Product Owner to make the decision to terminate the Sprint and replan.