How to remove unused, specific tab

I’ve created three custom tabs and filled them up with the content (via products mass import) but now I would like to delete one of them, specific tab.
Is there a way to do that? I can do that manually when I edit product but the problem is that there is ca 20K products.
In a database I can see all of information (about all of my tabs) in one field. I can hide this tab from viewing in product view but I would like to delete data and clean up database. Is there any solution for that?