How to reduce phlem in bronchiecstasis?

May be difficult. Some of the therapeutic measures include agents that will help to liquify the sputum and make it easier to cough up. Some have used inhaled aerosolized antibiotics (systemic antibiotics are seldom helpful because they do not get to the bronchiectatic areas). This is a chronic incurable problem. If there are localized areas they may be amenable to surgery. See a pulmonologist.
Keep lungs clear. Best thing to do is to always keep your lungs clear. You will always have phlegm in bronchiectasis. This is part of the disease. But, you should keep your lungs clear of phlegm as much as possible. One of the best meds for this is Mucinex (guaifenesin) or robitussin. It helps thin the phlegm out so you can keep your lungs clear. If the phlegm increases in amount, color, or you cough up blood, see your doc!