It would be really useful if we can turn off (remove from display like when we click an item on legend) each column element in column bar chart.

This could be useful in many cases. Consider a graph with a column of very large numbers and very small numbers (example http://jsfiddle.net/uqA6w/1/). Turning off the column with large numbers (Jan in example) will improve the resolution of other columns a lot. You can zoom, but this is not convenient as you may have to zoom. multiple times. There are even cases where you want to draw a graph with many column, but later filter the columns and save it etc.... Turning off the column is the perfect solution here