Change All for a box

Hi, Was hoping to do a universal change all for a box in Quark 9.5.4.1 that was given a point on the bottom using the select point tool. I'd like to remove that point so the box becomes a perfect rectangle. I can go through manually, select the box, go to item--->shape and change it from the sixth shape down to the first one. Is there a way to do this quicker for all boxes in the layout? Appreciate any and all help.