Hello,

It is not possible to display only the relevant brands in a filter. But this functionality is already provided that when you are not in the shop page and inside the specific category then only those filters shown which have some products from that category.

The only way to hide the brand logos is to directly remove the images from the Product>> Attributes>> Brand. Edit them one by one and remove their images as in the screenshot:
https://jmp.sh/EaxDbnP

In result image for that brand will not shown only the text will shown: https://jmp.sh/76RPhsl

Also if you used the latest version of theme and display type of brand filters as drop down from the widgets then the logos automatically hidden as in the screenshot: https://jmp.sh/D81GlAj

Best Regards.