In what way can I lose 30 lbs in about a week?

Not going to happen. A pound is roughly 3000 calories, or a bit more than a normal days caloric intake for a 200 (pyrethins and piperonyl butoxide) lb active adult. Drinking nothing but water for a week, might let you drop 7 pounds. Exercise might increase your losses, but would be unsustainable without some calorie intake. If you choose to diet, get a physical, plan realistic goals and try to lose 30 lb in a year.