You can calculate watts from kilowatt-hour and hours. You can't convert kilowatt-hour to watt unit since kilowatt-hour and watt units represent different quantities.
The power P in watts (W) is equal to 1000 times the energy E in kilowatt-hour (kWh), divided by the time period t in hours (hr):
P(W) = 1000 × E(kWh) / t(hr)
watt = kilowatt-hour / hour
W = 1000 × kWh / h
What is the power consumption in watts when the energy consumption is 15 kilowatt-hour for time duration of 3 hours?
P = 1000 × 15 kWh / 3 h = 5000 W