Have a look here, basically there is no configuration recovery on industrial routers (for an obvious purpose, since they often sit outside, in loosely-controlled places)
https://www.cisco.com/c/en/us/td/docs/routers/access/800/829/15-6-1TIR8xx-Release-Notes.html#pgfId-1058370
You don't need to disable the reset button:
- it's a pinhole, so you must use a pin to push it, hence no accidental press possible
- someone who would use the button to reset the router to factory defaults, for a physical DoS, could as easily unplug it from its power source
This behaviour seems to be "by design".
So save your config after every modification and stop worrying about config recovery.
Check the documentation for your exact IOS versions, since there have been some modifications in the way the button works.