cant remove old/non existing email from icloud info

so i have 2 devices with an old email that no longer exists. it was my old comcast email. that account no longer works so i cant access my i cloud. i made a new one because it required me to. i would like to know what can be done. i cant delete or sing in with the old one because the whole accout no longer exist. its like its stuck on my ipad and wont delete to put my new one in