Looks like 'metadata' is a list of dashboards (and sheets?) that are used in the story and I don't see a way to remove it
I'm going to venture that currently at the bottom of your workbook there is something like a million kajillion tabs. What you need to do is to right click each dashboard and choose 'hide all sheets'. Then you need to right click the story and do the same and then republish.
This should fix it. I checked a dashboard I have on public and I only show 1 item in the metadata even though several sheets are used. However this is on a dashboard level and not at a story board level. At the worst you'll have a list of dashboards with this fix.
The other solution is obviously going to be to use tableau server or tableau online. Pay to have control over what the clients see. I see you've disabled the download option and I assume that the data might be sensitive then. Just be wary that there have been issues in the past where workbooks even those you checked could not be downloaded were downloadable. Tableau Public is a free service and it is not really intended for production and client confidentiality items.
Brilliant! Thanks Carl. Such an easy solution - i should have thought of that :-)
I was aware of the issue with workbooks being downloadable even when not intended to be. So the underlying data has been aggregated and small cell sizes have been randomly rounded to protect confidentiality. Thanks for cautioning me though - confidentiality is a real concern for me.
Thanks again!! I really appreciate it.