So far I haven't found a way to turn it off. Best I can find it to "remind me later" in tiny font at the bottom of the page. Same problem, no non-Comcast emails and cell phone already associated with my account.
Not alone at all; there are a bunch of us caught in that trap. It'd be real nice if those of us who can't provide usable answers to those questions could just turn it off! Using the "remind me later" link does hold it at bay for a while, until I clear cookies or my cache.
Thanks for reaching out. @Welcome_to_Post is correct. At this time, there is no way to disable this feature other than clicking on "Remind Me Later". Feel free to share your thoughts and feedback on why adding another way to dismiss this would be beneficial to you and other customers by following this link.