Place the rest of the tiles on the wall, leaving the partial tile for the end of the tiling job.
Take the tile that you intend to trim and place it over the tile adjacent to the partial space against the cabinet, overlapping the other tile entirely. Slide the tile toward the cabinet, stopping once you reach the point where the partial tile will end. You’ll need to leave a gap against the cabinet as wide as the joints between your other tiles, so stop moving the tile toward the cabinet when you reach the point of that gap placement.
Mark a cutting line across the tile using a marker at the point where the tile you wish to cut overlaps the already placed tile. Keep the joint gap in mind on this end as well, and position the mark so that there’s enough space for the gap on that side of the partial tile as well.
Remove the marked tile from the wall and move it to the tile saw. Place the tile onto the platform of the saw with the blade of the saw aligned with the cutting line. Turn on the saw and move the platform toward the blade, cutting the tile with the blade. Turn off the saw and remove the tile for mounting to the wall.