If you just want to transform the midi+Sample One to audio, right click on the Sample One track and select ‘transform to audio track.’ If you want to record the audio output of the Sample One track back into another audio track, that’s a bit more complicated.
All of that said, if you have Sample One inserted into a track, have a sample loaded, and you have midi notes on the timeline triggering Sample One, you don’t really need to transform to audio until you are ready to mix and master your track.