The correct action to take is to implement a Durable Function orchestration with a Timer start event.
Timer Start Event: A Durable Function orchestration triggered by a TimerTrigger ensures the cleanup process runs automatically every night at a specific time without requiring any manual intervention or external dependencies like Postman.
Built-in State Management: Durable Functions split long-running tasks into stateful steps (orchestrators and activities). This allows the function to efficiently iterate through thousands of old blobs, batching deletion calls safely without hitting execution timeout limits common to basic serverless functions.
Low Operational Cost: When hosted on the serverless Azure Functions Consumption Plan, you only pay for the exact execution time your code runs. The orchestrator yields compute costs while waiting between sequential activity deletions, keeping your expenses minimal.
Reference:
https://learn.microsoft.com/en-us/azure/azure-functions/storage-considerations