You cant, unless you cut off a heavy body part. You didnt put that weight on in a week, so dont expect it to come off in a week. To lose weight you need to do at least 30 mins of cardio every day. You also need to eat healthy portions of healthy food. Stay away from processed foods and stay away from soda's.
Calorie counting helps although you can't lose that much that quickly and even if you could, that wouldn't be healthy. Heres the site I used https://www.supertracker.usda.gov/default.aspx just make sure you keep your account updated. It helps if you just leave it up on your computer. Excercising can also help just don't overdue it or you might get hurt or discouraged