You can adjust the widths of the columns of a grid to hide trailing columns. In "Interact" mode, a small draggable handle appears between column headers:
You can reset the columns to their default uniform spacing with the "Reset Widths" button in grid properties.
Manually resizing column widths enforces a minimum size. You can set column widths to 0 programmatically via "grid.widths", but a 0-width column looks a bit odd; I'll make a note to fix that in the next release.