>So does this mean you can add a column at design time, but you cannot delete the column once it's been added? Only deleting at run time?

Yes, exactly.

If you have a parent class, say, container with several textboxes, and then put it on a form, you would not be able to delete one of the textboxes in this instance of the container in the design time. In run-time you can use RemoveObject command.

Since you're getting this error it's obvious, that you're trying to create an instance of the predefined grid class. So, if you can not fix that grid class, your only option would be deleting this column in run-time (or making it invisible).