I have all devices but not original packaging. I can deliver to a COMCAST office, but need listing of what is needed; i.e. wires ect.
You don't need any packaging, just the devices themselves. They'd probably appreciate getting the power cords and remote controls as well, but returning devices is the main thing. You don't need to return any HDMI, coax, or Ethernet cables, or any splitters or amplifiers.
If possible, get written confirmation that your account was closed, as they sometimes "forget". Be sure to get a receipt for the equipment you return and keep that receipt forever. Comcast is in the habit of "forgetting" that equipment has been turned in and billing you for it months or years later.