Sorry, but rearranging sheets is not currently supported. It was an oversight in the original design, and adding it now would be complex since you have to ensure everything (from formulas to charts, to pivot tables, whatever) moves when you move the sheets. As this is a very little requested feature (in fact, I am not sure if this is the first time I hear about it, even if I was aware of the limitation), some other features have priority.
For simple and not really linked sheets you could insertandcopysheet() and then deletesheet() the original, but you will lose references.
As said, this is in the todo list, but with very low priority