Xfinity Log ons

> How do I stop Xfinity from using my home as a hotspot for others?

   Talk to Xfinity?  They have almost complete control over that sort of
thing.  At one time, I thought that they offered a discount if you
allowed them to do that.

> [...] how can I use only plugged in wifi, not streaming? Is there a
> router setting to turn off?

   What does "plugged in wifi" mean to you?  Wi-Fi is, by nature,
wireless.

      https://en.wikipedia.org/wiki/Wi-Fi

   If you mean that you don't use Wi-Fi, only wired (Ethernet)
connections, then you may be able to disable the radios.

   Visit http://netgear.com/support , put in your model number, and look
for Documentation.  Get the User Manual (at least).  Read.  Look for
"Control the WiFi Radios" and "Enable or Disable the WiFi Radios".
Further reading might not hurt, either.

   I don't know whether that will disable the Xfinity hotspot.

> Does anyone know if the USB plug is only for power out?

   People who have consulted the C6220 User Manual might know.  Look for
"USB".

> [...] It does not seem to be a cabled connection to use wifi more
> directly.

   Again, what does "wifi" mean to you?  The USB ports on these routers
are intended for use with a storage device (or, on some models, a
printer), not for any kind of network connection.

> Model: A6150|AC1200 Dual Band WiFi USB Mini Adapter

   Nothing to do with anything?