R6300 Cannot log into, want top change it to a WAP

> Want to add R6300 and make it a WAP,

   R6300[v1] or R6300v2?  Look for "Model" on the product label.
Firmware version?

> cannot log into it

   What happens when you try?

   "cannot" is not a useful problem description.  It does not say what
you did.  It does not say what happened when you did it.  As usual,
showing actual actions (commands) with their actual results (error
messages, LED indicators, ...) can be more helpful than vague
descriptions or interpretations.

   Visit http://netgear.com/support , put in your (actual) model number,
and look for Documentation.  Get the User Manual (at least).  Read.
Look for "Reset" and/or "Factory Settings".  Then, for an R6300v2,
"Wireless Access Point (AP)".

   According to the R6300[v1] User Manual, that model lacks a WAP-mode
option, but that may not be fatal.  For an ad-hoc scheme to deal with
such models, see, for example:

      https://community.netgear.com/t5/x/x/m-p/1463500

That's written for a Netgear C6300-as-WAP, but the steps are about the
same for any other router (any make/model) which lacks a one-step WAP
option.  If the router which you're reconfiguring has a WAN/Internet
Ethernet port (unlike a Cxxxx), then leave it unconnected.