aws data exchange - managing products, datasets and revisions

I am trying to tidy up some old test datasets and products in AWS data exchange. Starting with 'owned datasets', when I click on the dataset, the 'delete' option is greyed out. How do I delete them? The product they were in has been unpublished so there are no subscribers (it was a free product just for testing purposes). The revisions also cannot be deleted - the delete option in the 'actions' dropdown is greyed out. The test product also cannot be deleted. I have full administrator access with full data exchange permissions added. I have also tried using the CLI delete-asset command and get a 'Cannot take action on a Finalized Revision' error, but I'm more interested in using the console. How on earth do you manage old products, datasets and revisions which you no longer need and for which there are no active subscriptions? Why are the console options not available? I can't believe simple administration tasks can be so convoluted and difficult. Can someone please help point me to some documentation or other material where this is explained. I can find nothing in the documentation. Many thanks for any assistance, Simon Fletcher