The only command in the code is: Table1.InitializeTable(NumberOfColumns As Int, cellAlignement As Int, showStatusLine As Boolean).
You cannot change it afterwards.
You can also set it in the Designer.
What exactly do you want to do, that you need to change the number of columns?
Because I Have in My application, that if You have privileges selects a jrdc query with 'x' columns , and if not, selects a query with 'y' columns, and then show it in the table.