According to a Comcast representative, anyone who knows the last 4 digits of the deceased’s Social Security number, their account number or the amount of their most recent payment can cancel a deceased’s account.
However, accessing that account will be more difficult. If you want access but do not know the password that was used by the deceased, you must go in person to a Comcast payment center. The representative with whom I spoke thought it would have to be a Comcast office in the area where the deceased lived. I pointed out that this is a bit ridiculous; for example, my father lived on the other side of the country. Did this policy mean that I would have to fly from California to New Jersey in order to find out what his password had been? I was told that the answer was “yes”. I would suggest that you go to the nearest payment center and try to get them to provide the needed information.
If the account is not cancelled Comcast will continue to bill the account holder indefinitely.
To learn more about how to handle someone’s online accounts after they die, as well as to identify things you should do to protect the identity of that person, check out the book “Grave Robbers…How to prevent identity theft of the deceased.”