The tool "Push / Pull" allows us to increase or decrease the volume of a solid, exactly pushing or pulling a face.
The same concept applies even if we want to push a face.
In this case push the face inwards. If we come up to 'other solid end face thrust be deleted and it will create a vacuum.
Nell 'example below I drew a little man out of a solid.
Then with the instrument "Push / Pull" I pushed my face I want to delete until its end,
at this point Sketchup has eliminated the thrust face leaving only our model.