Hello,

Please remove the earlier CSS in this regard that you have already applied and try the following Custom CSS on your Site in this regard:

#tab-title-additional_information {
    display: none !important;
}

Location to paste Custom CSS, go to Dashboard >> Theme Settings >> Custom CSS >> Global CSS section >> paste the CSS.

If somehow the issue still persists, then kindly please share your Site WP-ADMIN Login details in the Private Content field so that we can check this concern on your Site and help you out accordingly.

Best Regards.