Hello @Joshua Reineke Thank you for posting your question at Microsoft Q&A forum. Happy to assist!,
So, your questions is what happens to the data if the DPM server is removed from recovery services vault.
If you stop the backup and retain online data, the data will not be purged. If you just do decommission the DPM Server without any policy change, the data will be retained on Azure and will be purged according to retention, however will always keep that x numbers of the retention. If you do not need nothing of this you can go directly to the vault and delete the DPM server from the vault, with this will loose all the data but all will be purged.
Hope this answers your question!
----------------------------------------------------------------------------------------------------------------------
If the response helped, do "Accept Answer" and up-vote it