I've asked a Comcast employee to help you. You should expect a reply in this thread.
Hi, neogeo64 - I can remove your old modem from the online view. Please send me your full name, the account holder's name as it listed on the billing statement, a phone or an account number in a private message. Click on my name ComcastElla, then click Private Message Me.
@neogeo64 - I reached out to our community manager to enable the PM feature for your account. Apologies for the delay.
@neogeo64 - The PM feature is now enabled for your account. Please click on my name ComcastElla, then click Private Message Me. Thank you!