Hi Mohammed.... Welcome to healthcaremagic forum.
is a chronic condition having exacerabations and remissions. Treatment is basically based on preventing exacerabation, treating the symptoms during these exacerabations and avoiding the risk factors that can precipitate them...
If your father is symptom free, consult your doctor, who will plan to taper the medications. If symptoms don't worsen, then the oral medication can be switched over to inhalers. Lifestyle modifications and risk factor control however needs to be continued..