misc981 Greetings & Welcome to Microsoft Q&A forum!
Your understanding is correct regarding data deletion.
Data deletion is not supported. Data is immutable in AI Studio. Once you create a data version, it can't be modified or deleted. This immutability provides a level of protection when working in a team that creates production workloads.
One thing you could try is when creating a data source with Blob, you can select the Indexer schedule. See Create an index from the Indexes tab for more details.
Also, see How to add and manage data in your Azure AI Studio project if it helps.
Do let me know if you have any further queries.