How many calories should I eat a day to lose 5 pounds. I'm 5'6 & weigh 140?

500kcal. We estimate that it takes an extra 3, 500kcal intake above output to gain a pound of weight. Conversely, you need to burn 3, 500kcal beyond what's consumed to lose weight. On a daily basis, you're looking at 500kcal difference to lose a pound a week. That doesn't mean starve but rather a combination of less in and more out.
Need more info. To determine this you need to put your information into the harris-benedict equation to calculate your basal energy expenditure. You can find this online. It takes into account gender, age, height, weight and activity level. If you find your daily caloric intake and subtract 500 calories by either decreased food or increased activity, you should lose about a pound a week. That is usually safe.