Well, if you have already tried to edit the sidebar.php of the theme but could not get the meta or the archives removed from it, I would suggest you to check the "Widgets" section. It might be possible that "Widgets" are enabled in the right sidebar. You need to remove the meta and archives Widgets from the right sidebar. Once you remove it, you will be able to disable the meta and archives Widgets from the right Sidebar.
Hope this will be helpful
Best of luck!!