On the Galaxy Tab it's not possible to disable the number keys. That's a pity because it makes the letter keys below become much smaller. Strange actually, because the option to hide numbers keys is there on the Galaxy phones, why isn't it there on the Tab? Personally, I don't need the Del key next to the numbers either, it's confusing when you also work on iPad which has the backspace on the top right.
Samsung, can you give us the possibility to hide the number keys on Galaxy Tab just like on the Galaxy phones?