@Alex Roca Thank you for leveraging Microsoft Q&A platform for raising concerns related to Backup vault with immutability lock.
Thanks for your time over the call with our support professional. Sharing below the summary of the issue and the resolution provided.
Issue: Problem deleting the backup vault
Cause: Immutability is locked
Resolution: Tried to delete backup instance and it is deleted successfully and goes into soft delete state.
-Suggested @Alex Roca to wait for 14days and thereafter, he should be able to delete the vault.
Hope this helps others looking for solution to similar issue.
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