Hello, @lucam997,
Actually, the above CSS was tested on my test site and working fine for me, but not on your site, so please try with the below-given CSS code and check back to your site after removing the browser cache.
.term-description.et_second-description {
display: none !important;
}
And if still it will not work for you, then please share the WP Admin Login details of your site in the private content area of this topic, so that I will solve it for you on your site.
Regards 8Themes Team.