How do you lose fat without exercise?

Eat one meal a day. The same time each day. It will ruin your metabolism but you will lose weight. or practice one of many forms of vegetarianism. Along with that give up processed foods like potato chips and white flour products.

Eat foods such as apples. Your body actually has to burn more calories to break them down than the apple has. Drink plenty of ice-water. Don't eat before going to bed unless it is a light yogurt or cheese stick. Stay away from alcohol, soda and fast food. You'll see a change in two weeks.
instead of eating fat and junk food give that up. eat fruits and veggies and it won't kill you to give up food because as long as you are eating something you won't die.

Reducing your weight without exercise can be done but is not the best and most effective way. Also there are limits to how much you can lose without a negative impact on your health.
The basic principle is to have a negative calorie intake, this mean you eat less than you use. Cutting out fat, sugar, complex carbs (pasta, rice, Bread, etc) soft drinks, alcohol is a very important part of losing weight. Trying to increase protein and vegetables is also very important, as the protein will give your muscles enough energy so that they don't get wasted away. The veg intake will provide a light amount of carbs and also vital vitamins, minerals and nutrients that help the function of the body.

Everyone burns calories on a daily basis when doing everyday activities such as walking, shopping, cleaning, etc so trying to increase these activities will help also.

I would personally try this over a short period of time maybe 2-4 weeks while trying to increase my activity. This could mean going for evening walks, doing gardening or other physical activities, these are the key to maintaining weight loss.

You can also use meal replacement supplements, protein supplements, amino acids, vitamins and fat burners. All these can be used to help you lose weight and maintain health.