The primary column

You have noticed that you can not move the leftmost column out of its position. That is because this column is a unique column called the Primary column. 

The primary column intends to hold unique names for each of the different people, objects, or ideas that you are tracking in the sheet. 

In the Lookup sheet, you can Rename the primary column and change the column type, but you cannot remove the primary column. However, in the Time based sheet, you do not have options to edit the column header.