Remove header columns in Page 5.0 In the new iWork Pages, there is by default 3 cells or columns in the header and I cannot remove the column back to its original one column header just like the normal header in Pages 09'.

If you see that in the image, it is NOT a table, but the header when the cursor hover on it.
In fact what Apple did here is better than before : 

If you write in only one of these 3 columns it behaves as if there were only one column.