Disable the 5Ghz radio on the R7000 Nighthawk

> Model: R7000|AC1900 Smart WIFI Router

   Firmware version?

> I need to disable the 5Ghx radio only. [...]

   Says who?  Why?  ("GHz".)

   General advice: You might have more success if you described the
actual problem which you are trying to solve, rather than asking how to
implement some particular "solution" ("disable the 5Ghx radio"), which
may have little or nothing to do with the actual problem (whatever it
might be).

> [...] I do not see any radio switch buttons when I access the router
> itself. [...]

   Where, exactly, were you looking?  "access the router itself" how,
exactly?  Web browser?  Some app or other?  Other?

> [...] Spent 2 hours on hold before I threw in the towel.

   That time might have been better spent using a different technique
(which can be used in parallel with not talking on the telephone):

      https://en.wikipedia.org/wiki/RTFM

   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".

   Whether doing that makes sense is, of course, still an open question.