The login link is part of the "secondary" menu; the link appears by default if you haven't specified anything for the menu.

You can customize or modify the default menus in Annotum by following these instructions.

And one "secret tip": If you really want to have nothing appear where the login link is now (and not some other links), simply create a new menu as described in the documentation, and add only one item to it - a "custom link" - with the value "#" (no quotes) for the URL and a single blank space for the label. Click add to menu, then save menu, and the login/log out link will be gone!