Multiple attempts via Xfinity app to have my old modem removed, now trying here! :)

I recently had my service upgraded to X2 speeds, and updated my old modem (Netgear CM-1000) with a new Arris S34 to utilize the speeds.  I've since tried THREE SEPARATE times to have the old CM-1000 removed from my account via the app and/or the website, but whenever I pull up my plan in the Xfinity app, sure enough, still shows under troubleshooting steps, and every time I mistakenly click on the "upgrade equipment?" link, it still shows as an option to choose against.  How can I have that old modem removed for good?  I'm giving it to a coworker, and do not want it associated with my account in any way moving forward.  Please advise.