Hi @Jack Shilling ,
Something here might help:
Cancel your Azure subscription
https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/cancel-azure-subscription
How do I delete my Azure Account?
https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/cancel-azure-subscription#how-do-i-delete-my-azure-account
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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Best regards,
Leon