Why cant I delete a column in Numbers?

I've always had this issue on almost any file, I can't delete a column in numbers for no apparent reason. I have two columns and I need to delete the second column which is blank. But for some reason, I can delete the first column that has all my info in it.

Screenshots below (data replaced with fake data) showing that the first column can be deleted for some reason, but the second cannot. The second column is completely empty top to bottom. I've searched far and wide for years and never found a good answer (except to use a different program).

The column is not locked, I've tried manually setting the columns to only 1, and it won't budge. What is going on? How do I fix this?