D-Link products don't have a log out button. There is a built in time out feature of the web page that will automatically log the connected user out of the web page. Usually about 3 minutes. Has varied per product.
Accessing the Modems web page can only be access by the LAN side devices at 192.168.1.1. Unless you enable Remote access, then you could access the modems web page from a remote location, like work.