@LeeJordan Thank you for contacting us on Microsoft Q&A platform. Happy to help!
As per the error message it seems your server got registered with incorrect backup management type which needs to be corrected from the backend. After the changes then you would be able to delete the server from recovery service vault.
Unfortunately, you have to open a support request with Azure Backup Team to get this corrected as you don't have a way to correct it from your end. Request you to please check and maybe open a free ticket with Azure support to get this fixed.
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