How to Remove Category Name on Post Thumbnail

That is a feature specific to your theme. Unfortunately, because the theme is only available commercially, it isn’t likely that many folks here would have access to the theme files. Your best bet is to consult the usage documentation that came with your download for tips on how to customize the theme. If that isn’t a feature that can easily be controlled by the user, you will need to contact the theme developer through the support channels they make available at the point of purchase.