@PeterP1550 - Thanks for the question and using MS Q&A platform.
Assuming your storage account's type is either General Purpose v2 (GPv2) or Blob Storage, you actually don't have to do anything by yourself. Azure Storage can do this for you.
You'll use Blob Lifecycle Management and define a policy there to delete blobs if they are older than 30 days and Azure Storage will take care of deletion for you.
For more details, refer to Configure a lifecycle management policy.
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