Hi Nij0!
Try adding this to your custom CSS.
.avia_wpml_language_switch { display: none !important; }
If that does not work then send us a link to your page and we’ll take a look. You can set your reply as private if you wish.
Best regards,
Elliott
FYI I tried adding the CSS Elliott provided, but it did not have any effect on my site. However, the following CSS did the job for me:
#avia-menu .av-language-switch-item { display: none !important; }