You'd have to play around with the theme files. A while ago, I merged two themes to combine the best of both themes. It wasn't a heavy lift, mostly trial and error.

I put my recalbox out of service long term until there's support for Pi 4 to install my Pi 3 in my MAME cabinet, otherwise I'd get you the exact code to get rid of the line. I believe you need to set opacity to 0.

Despite being a separate system, the retropie wiki has excellent instructions on how to modify the theme files.

Tu peux y laisser les 2 fichiers txt qui te renseignent sur le format des roms à fournir à chaque émulateur. Il y a une version FR et EN.
Le reste, les roms, le gamelist.xml et les dossiers download images (si les jeux ont été scrappes) peuvent être supprimés si tu veux faire disparaître une console du carrousel.

Ok merci du conseil.
Je me lance.

@azvarel sorry !

Anyway you can use Universal Xml Scrapper available there to do custom mix profile referencing several images to display more than just one
https://forum.recalbox.com/topic/4690/soft-universal-xml-scraper-v2

Examples of a custom theme using this :
https://forum.recalbox.com/topic/5786/theme-mix-foolscreen

Yep I see that 😉

(And send it to rockadd**ket 😉 )

Maybe in 4.2 😉