Killink CSV provides the following ways to resize column widths:

Manual Resize

When you move the mouse cursor over the column separator line the cursor will change to the resize column cursor as seen in the picture below.  Move the mouse cursor over the column separator line, and click and hold the mouse button while moving the mouse to the left or right.  Move the mouse to the left to make the column width smaller, or move to the right to make the column width larger.

Note: You an hide the column by moving the mouse to the left until the column is no longer visible.

Best Fit

Double click the column separator line to change the column width to fit the contents.

Auto-size to Best Fit

Mark the program option "auto-size columns to best fit" to have the each column's width resized to fix the contents when the file is open.  This option is available by pressing the F8 key or selecting Tools > Option from the menu,