To answer your question in body of your thread, reduce your caloric intake.
However, you proffered a different question in your topic title: How to lose weight without losing muscle. To do that, you have to ramp up your lifting. When you lose weight without any sort of exercise, you lose both fat and muscle. To keep the muscle that you have, you have to strive to get as big muscle-wise as possible. That's the only way that you won't lose muscle mass.