I am trying to convert from 192kHz to 96kHz or possibly 48kHz, but don't want discarded higher frequencies to alias.

*Any recommendations?
*Would you recommend using a low-pass filter to remove the unwanted high stuff prior to downsampling?
*If so, at what frequency should I start removing with the filter?

 

A proper samplerate converter.
Can be found here: https://src.infinitewave.ca/

Yes.

So that it effectively removes everything above the nyquist frequency but not what is in the audible range of human hearing ~22kHz.

 

I have some users claiming that many of the editors and DAWs have a built-in low pass for the conversion, but . . .

 

Unless explicitly stated otherwise, every downsampler will automatically filter content past the new Nyquist limit. You'd have to go way out of your way to find one that doesn't by default (-> the depths of hobbyist projects and building blocks intended for developers)