Reaper has a noise reduction tool, as do all audio editing and recording programs (I'm assuming. I've never seen one without that tool). 

HOWEVER, the tool is not called Noise Reduction. Oddly that function is part of a tool/effect called ReaFir.

The links I mention in the episode are:

For the blog post: https://www.homebrewaudio.com/9603/reafir-madness-hidden-noise-reduction-tool-in-reaper/

For the YouTube video: https://youtu.be/HEY9XIYJtGg