You cannot, unless your first "h" (in amph), is a msitake. If you really mean, convert Whr into Ahr, then you need to divide the Whr figure by the voltage.
You don't! A watt hour measures energy,...
Watts = amp x volts. As you can see by the formula you have parameters missing. You need a number for the voltage so that you can calculate the amperage. Amps = Watts/Volts
You cannot convert...