One workaround is to use Storage explorer, filter the files with prefix and select all, delete.
If this delete activity has to be scheduled, then ADF can be used.
If you want this feature to be implemented, you may post the feedback here which is monitored by product team
https://feedback.azure.com/forums/217298-storage
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Please don't forget to Accept Answer and Up-vote if the response helped -- Vaibhav