If you don't plan on using the Kiwi tables for the sizing chart and wish to provide your own images and text but still want the nice benefit of Kiwi's pop-up modals, then what you can do is on each sizing chart page, delete the table layout block.

If you move your mouse over the size chart layout, you'll notice some control links appear. You can click "Delete" to remove the table layout from the size chart.

Then you can click on edit for the "Images & Text" block, and start adding any images or text as you wish without displaying the Kiwi tables.