Will it be a 24h weigh-in or will you be competing the next morning? There are a variety of ways to drop even a significant amount of weight by getting rid of excess water or glycogen. I dropped 15lbs in a week's time by water removal with water and salt and glycogen depletion for a 24h weigh-in.
Basically you drink a shitton of water and ingest around 5g of salt for two days, cut the amount of water and salt by 50% for two more days while also cutting carbs down to around 100g and finally no salt, 50g of carbs and a lot less water.
In your case however, I'd probably just eat less carbs and go to sauna a lot more. It has less impact on your performance if it's not a 24h weigh-in.