Answer
Go to the Lobby Overview window, right-click the lobby page, and select Edit to check whether the page is currently editable. If it's locked, choose 'Edit Anyway' and confirm the padlock icon turns green (editable). With the page now editable, open it, unlock the padlock, remove the specific lobby element you want gone, then lock the padlock again to save your change. Afterward, repeat the first step to restore the lobby's original Editable/locked setting, since 'Edit Anyway' is meant as a temporary override rather than a permanent state change.