Deregister cell phone from panasonic KX-TG7731 or KX-TG294SK

This is for the Panasonic cordless phone KX-TG7731. There is another model number along with the serial number KX-TG294SK

The options on Panasonic support site, don’t work, but [MENU] [1] [3] [4] works!!

Thanks to justanswer.com found the answer in an already answered question http://www.justanswer.com/phone-systems/97tff-want-deregister-cell-phone-no-service-panasonic.html#re.v/288/