Inside the Inventory and Order pages, Columns can be added or removed. In both tables, the columns menu is in the same location, second blue button from the left with a pencil icon on it. (I am using the order page columns as an example here)

Pressing it opens a new pop-up window with column names and checkboxes near them.

Select or deselect the fields as you see fit and press Save.

Please be aware: Increasing the amount of visible columns will slow down your loading speed. Also, enabling all of the fields will require scrolling the table to the right to see everything on smaller screens.

Alternatively, you can remove all, but the most important function columns.

Order, Icons, Action in Orders and Store, Name in Inventory.