Is there a way to disable the delete content box when deleting a cell?
Sometimes i use backspace others i use delete, so changing to legacy or not does not work, i want to disable it
(Assuming you are not editing a cell. Otherwise backspace has a completely different meaning.)
Change your habit. The two commands are for different purposes.
This is similar to the difference between Ctrl+V for Paste and Ctrl+Shift+V for Paste Special.
The one executes a default variant, the other allows for choices.
