In your project, swipe up to expand the track stack to display previously recorded tracks.
Note the track you want to trim and then toggle the button in the top left hand corner, so you're in the Edit view, if you’re not already in it.
Select the noted track number or name in the selector strip by opening the dropdown from the associated icon, then choose 'Adjust Track Trim.' Drag either end of the track to trim as needed.
Once completed, select Done and expand the track stack view again to see that your track is trimmed successfully.