It's not the first question addressed in the FAQ, but there is this answer: "Yes, you can request to delete data associated with Amazon One through the device

It's not the first question addressed in the FAQ, but there is this answer: "Yes, you can request to delete data associated with Amazon One through the device itself or via the online customer portal at one.amazon.com. We believe customers should always be in complete control of when and where they use the service, and we designed Amazon One with this in mind." Perhaps, as the sibling comment suggests, this was an architectural decision made based on the requirements for operating in the EU.