I am unable to delete rectangular shape covering formulas in Numbers

I have a column of formulas that I want to protect from being altered by other users. I tried to use a rectangular shape positioned over the column. That sort of works, however, when I try to turn off/delete the shape so I can edit the formulas, there appears to be no way to do that. I am not able to move or reduce the size of the shape. I am stuck with the shape, and it seems my only choice is to start from scratch and re-build the spreadsheet. It is a complex sheet so hopefully there is a way to delete the shape. My recommendation: don't ever use shapes for this purpose. Unfortunate, because apparently there is no straightforward way to protect cells in Numbers.

[Re-Titled by Moderator]

Original Title: Deleting Shapes in Numbers