You cannot manually do it. The most you can do is to disable the SSID broadcast, but if you truly just dont want the wifi or want to bridge the device to use your own router you would need to give us a call 800-363-2416 and we can take care of it for you.
That's exactly what I want to do. My EMTA is down in the basement in the very corner so I can backfeed the telephone line. It's wifi only reaches a small portion of the house because of this so I want to use my own wireless router upstairs and bridge the internet with Powerline networking equipment.
Can I not do it via the advanced page at 192.168.100.1? I just need the password of the day