You can disable the ability to make changes or cancellations PER EVENT... when editing the event, go to the User Panel tab and disable Cancellation. Then it won't show. The Cancel column will still be in the user panel, but no buttons will show. To remove the column completely, you'd need to modify code. I'd suggest leaving it as-is and just disable the functionality.
Thank you for your quick reply. I found that configuration item but actually it seems that it has no effect. I tried both "yes" and "no". With both adjustments the cancel button is visible and usable. I also tried to allow cancelation and applied Last Date to cancel to the past. However canceling the event is still possible.
You must not have the latest version of DT Register. There were issues in the past with those user panel settings. The latest build would not have that problem.